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Full text of "Fishing Boats Of The World 2"

FISHING BOATS OF THE WORLD: 2 



FISHING BOATS 

OF THE 

WORLD:2 



Edited by 
JAN-OLOF TRAUNG 

Chief, Fishing Boat Section, Food and Agriculture 
Organization of the United Nations, Rome, Italy 




Published by 

FISHING NEWS (BOOKS) LTD. 

LUDGATE HOUSE, 110 FLEET STREET, LONDON, E.C.4, ENGLAND 

1960 



COPYRIGHT, I960 

by 

FOOD AND AGRICULTURE ORGANIZATION 
OF THE UNITED NATIONS 



AH right! 

First Published 1960 
1st Reprint 1967 



The views expressed in the papers and discussions are those 

of the contributors and not necessarily those of the Food and 

Agriculture Organization of the United Nations 



EDITORIAL TEAM 
Associate Editor: N. Fujinami 

Technical: D. A. S. Gnanadoss Translators: J. Chaux 

P. Gunner P. Frances 

P. Knoops 
H. Svenkerud Secretarial: S. Benoit 

B. Borland 
Style: P. Andrews C. de Frcitas 

C. Day D. Fisher-Knoops 

C. Davics J. OarTncy 

L. Jo vane 
A. Perez-Ortiz 



FROTBD IN GREAT WTTA 
UNWIN BROTHEM LMTtD WQK1NQ AMD LONDON 



CONTENTS 



LIST OF CONTRIBUTORS 

NOMENCLATURE AND SYMBOLS .... 

PREFACE B. R. Sen 

INTRODUCTION D. B. Finn 

CHAIRMAN'S NOTE . . . . A. C. Hardy 



PART I TACTICS 



Principal fightag boat types . . A.C. Hardy 

Grouping of boat types 

Variety of boat types within countries 

Change in appearance 

Common' types of boat 

FISHING METHODS AND DECK ARRANGEMENT 
Parse seining: deck design and equipment 

P. G. Schmidt, Jr. 

Basic purse seining systems 

Method of carrying fish 

Size of boat 

Requirement for an efficient purse seining system 
Basic design considerations 

Combination fishing 

Equipment for purse seining 

Analysis of vessel types and methods as applied to 
important purse seine fisheries .... 

U.S. East and Gulf Coasts 

Norway 

US. West Coast, Alaska and Canada 

West Coast of South America 

Iceland 

South Africa and South West Africa 
Portugal, France, Spain and North West Africa 

Angola 

Japan 

Korea 

U.S.S.R 



Drift Mittaf * deck 

Fishing ear 



/. C. de Wit 



Bow rudder . 
Hufl form . 
PtoptiWon machinery 



Page 

No. 

11 

17 
19 
21 
23 



27 
27 
27 
28 
30 



31 
32 
35 
35 
36 
37 
37 
39 

40 
40 
43 
44 
48 
49 
53 
53 
54 
54 
54 
55 



56 
57 
59 
60 
61 
61 
62 



Gillnet filing: deck 



T. E. Colvin 



Y. KanasasM 



Fishing gear .... 

Deck arrangement .... 
Main specifications .... 

Construction 

Problems affecting the fishing industry 
Future developments 



LongUne fishing: deck design and 

Fishing year . 

General arrangements 

Main specifications and construction 

Machinery 



Pole and line fishing: deck design and equipment 

S. Mwamatsu 

Skipjack 

Fishing method 

General arrangement 

Mackerel 

Fishing method ....... 

General arrangement 

Squid 

Fishing method 

General arrangement ...... 

DISCUSSION NON-TRAWLING . . . . 

Boat types 

Non-trawling fishing 

Drift-net and gillnec fishing 

Lofiglinifig ........ 

Pole and line fishing 

Combination fishing ' * 



Trawling ; deck dcdga and eqdpmmt 

A . von Brandt and C. Birkhoff 
Gaiend description of fishing gear . 
Bottom trawl with one boat . 

Sidctrmwtef 

Stern trawier without a ramp . 
Stem trawkr with a ramp 
Bottom trawl with two boats . 

Mid-water trawier 

Future prospects . . . , , 



fagf 

No. 

64 
65 
67 
68 
69 
71 
71 



73 
73 
74 
77 
82 



84 
84 
84 
85 
89 
89 
91 
91 
92 
93 

94 
94 
94 
95 
97 
97 
99 



102 
104 
105 
106 



108 
111 
112 
113 



CONTENTS 



COMMAND OF OPERATIONS 

f+ + mm j jiiinj _ujinB B^ 4 .I i In 

VOTOTUUOT OUUUU1 OT UBWJCTI 

.4. C. Hardy and H. E. H. Pain 

Basic components 

Typical layouts 

DISCUSSION TRAWLERS 

Review of related papers 

Stern handling versus side handling .... 
Hauling speed and winch power .... 

Smaller stern trawlers 

Future developments 

Command of operations 



Page 
No. 



114 
115 
118 



121 
123 
126 
127 
132 
132 



I PART II CONSTRUCTION I 

SCANTLINGS 

Steel and wood scantling tables (West Coast 

of U.S.A.) H. C. Hanson 137 

Wooden construction 137 

Steel construction 141 



Structural testing of small craft 

Y. Otsu, N. Yokoyama and T. Kobayashi 

General description 

Structure test 



Suggested standard scantlings . D. S. Simpson 

Hull timbers 

Determination of scantlings 

Fastenings ........ 

Determination of fastenings , . . . ' 

DISCUSSION SCANTLINGS 

Good boatbuilding practices 

Comparison of wooden scantling regulations 
Resistance of wooden keel, stem and stern post . 
Steel scantlings ....... 

Author's replies 

NEW MATERIALS 

Glass reinforced plastic hails . P. de Laszlo 
The raw materials of Polyester/Mat laminate 

Moulds 

Temperature control 

Inspection 



Rigidity 

Hollow skegs . 

Weight .... 

Tanks and engine foundation 

Repair .... 

Cost of hulls . . '. 



DISCUSSION PLASTICS 



146 
146 
148 

152 
154 
158 
159 
166 



167 
171 
184 
185 
185 



188 
.189 
189 
190 
190 
191 
191 
191 
191 
192 
194 
194 



FISH HOLDS 
The care of the catch 

C. A. Reay andJ. M. Shewm 

Why and how fish go bad 

Temperature control ....... 

Care and cleanliness in handling .... 

The fish room: engineering and architecture 

W. A. MacCallum 
Large fishing boats 

Insulation 

Features conducive to efficient and safe working 

Partitions, shelving, etc 

Coatings and linings 

Materials for fish rooms 

Small fishing craft 

Longliners 

Larger longliner, small trawlers and cutters . 



Icing versus freezing 



J. W. Slavin 



196 



The trawlers Delaware and Northern Wave 
Handling aboard the vessel 
Storage on the vessel .... 
Unloading and handling ashore 

Quality aspects 

Factors affecting costs .... 
Overall evaluation 



Tana freezing . C. Doke and S. Chigusa 
Methods of preserving the catch .... 
Refrigerating capacity and piping .... 
Insulation 

DISCUSSION FISH HOLDS 

Icing and related problems 

Design of fish holds 

Comparison of freezing installations .... 
Authors* replies 

INSTALLATION OF MACHINERY 

Propulsion engines for fishing boats . /. Stokke 
Comparison of two- and four-stroke diesels 

Supercharging of diesels 

Comparison of typical engines 

Influence of r.p.m. on length 

Semi-diescb 

Operation of engines 

Controllable-pitch propellers 

Installation examples and trawl winch drive 

Future development 

Steam versus dieed 

C. Hopwood and H. W. N. Meme 
Comparison of U.K. West Coast steam and diesel 

trawlers 

Example of machinery on a diesel trawler . 
Maintenance and operation of diesel main engine 

Winch engine 

Auxiliaries 



200 
201 
203 
204 



208 
209 
209 
214 
215 
216 
217 
221 
221 
222 

227 
228 
229 
230 
231 
232 
233 
233 

234 
234 
235 
236 



239 
244 
247 
258 



261 
262 
262 
263 
267 
267 
268 
268 
270 
272 



274 

275 
276 
276 
283 
284 



[6] 



CONTENTS 



Pag* 
No. 
CONSTRUCTION INSTALLATION OF MACHINERY 

(continued) 
Propulsion systems for motor trawlers 

F. SUberkriib 285 

Multiple-speed gear 285 

Controllable-pitch propeller 287 

Diesel-electric drive 288 

Propeller nozzle 288 



Ri 



ittmwlen ft tied with multiple reduction gc 



A. Chardome 
Auxiliary diesel for propulsion .... 

Breakdown of reduction gear 

Latest development 

Efficiencies 

Multiple reduction gear versus controllable-pitch 
propeller 

Device for raising and lowering propellers 



*p 

idJ\ 



K. Inamura and M. Ninomiya 

Structure and materials 

Installation 

Problems to be solved 



Vibration in trawlers . 

The modes of vibration . 
The nature of excitation . 
Determination of vibration frequencies 
Estimation of vibration frequencies . 

DISCUSSION MACHINERY 
Engine design in general 
Diesel-electric propulsion 
Multiple-speed gear 
Controllable-pitch propellers . 
Propeller shafts .... 
Authors* replies .... 



H. Lackenby 



289 
290 
290 
290 
291 

291 



295 
295 
296 

297 

298 
299 
299 
300 
301 



303 
304 
305 
308 
309 
313 



COSTS OF CONSTRUCTION 
An analysis of US. fishing boats: dimensions, 

weights and costs //. Benford and M. Kossa 320 

Weights 321 

Construction costs 325 

Proposed cost and weight system .... 328 



DISCUSSION COSTS 



332 



PART III SEA BEHAVIOUR I 

RESISTANCE AND PROPULSION 

Model tests of some fishing launches T. C. Gillmer 341 

Description of facilities and apparatus . . . 342 

Description of models tested 342 

Test results 345 

Model tests of small simplified boats 

K. Otsu, N. Yokoyama and T. Kobayashi 348 

Model tests 348 

Full-scale test 349 

Comparison with similar sized boats . . . 352 



An 



Model tests of five recent fishing boats 
The design of an improved hull form 
Propulsive factors affecting hull form 
Resistance and stream flow tests 
Effective powers for other sizes of vessel 
Velocities in the nozzle . 
Design of the propeller . 
Self-propulsion tests 

Delivered powers for other sizes of vessel 
Trawling tests .... 



/. T. Tothttl 



Aft. 

353 
3S3 
354 
355 
356 
357 
359 
359 
360 
361 
361 



Resistance of trawlers . * . H. Lackenby 364 

Methodical series resistance tests with trawler modeb 365 

Series A systematic variation of midship-section area 365 

Series B systematic variations in proportions . . 369 

Statistical analysis of resistance data for trawlers 

D. J. Dwst 370 

Theory of minimal variance 371 

Regression equation for trawler data . . .371 

Practical uses of the regression equation . . . 374 

The loads imposed by trawling gear W. Dickson 388 

Instruments used 389 

Method adopted during trials 389 

Explorer towing trials 389 

Mara towing trials 391 

Hauling trial 391 

SEAKINDLINESS 

New perspectives in sea behaviour G. Vossers 393 

Waves irregular phenomena 394 

Ship motions 3% 

Influence of main dimensions 397 

Influence of longitudinal radius of gyration . . 399 

Influence of bilge keels, sections, freeboard and sheer . 400 

Influence of metacentric height .... 401 

Vertical accelerations 401 

Motion in irregular seas 401 

Loss of speed 402 

Future developments 403 

Behaviour of trawlers at sea II . W. Mdckel 404 
Programme of investigations and the measuring instru- 
ments 405 

Power output and speed in good weather . . . 406 

The ship in a seaway 409 

The stability 411 

Rolling and pitching 414 

Remarks on the shape of Dutch coastal fishing 

Boats W.Zwobmm 418 

Speed and seakindliness 418 

Comparison with finer boats 419 

Comparison with fuller boats 420 

Fuel oil and lubricating oil consumption , . , 421 

Tests with a trawler model in wares 

/. D. van Manen> C. Vossers and H. Rijkcn 422 

Particulars of ship and model test conditions , < 422 

Results when trawling 424 

Results when sailing . . . . . . 426 



[7] 



CONTENTS 



SEA BEHAVIOUR SEA KINDLINESS (continued) 

Tke !! tit cioelHcieat . . J-O. Trmng 
Todd*s steam drifter tests 

NPL motor drifter torts 

Graff and Heckscher's trawler tests . 

Allan't drifter tests 

FAD tests 

Self-propulsion tests 

Wave tests 

Trawling tests 

Trawler ferns with bvlbow bows . D. J. Doust 
Resistance characteristics in calm water . 
Propulsion characteristic* in cahn water . 
Performance in rough water 

Tests of fishing boat models fat waves 

K. Taniguchi 

Methods and apparatus used in the experiments 
Effect of bow section form 



\ on hull design of fishing boats 

H. L Chapelle 

Resistance 

Seaworthiness and seakindliness .... 

STABILITY 

A method to determine freeboard in relation to 

stability O. Jablonski 

Principles of freeboard determination on the basis of 

stability criteria 

Graphical method for determining the curve KG, 
Determination of critical loadings for fishing vessels to 
construct a curve of KG 

Notes on stability . . . A.Takagi 
Statistics of fishing vessel insurance .... 
Trend in the principal dimensions of various types . 

Stability 

Comments on a few stability criteria 

Proposals for the assessment of fishing vessel's stability 



Transverse stability of tuna dinners 

/. R. Faulting, Jr. 

Effect of trim on transverse stability .... 
The transverse stability in longitudinal waves 



No, 



428 
428 
429 
430 
430 
430 
433 
434 
440 

445 
446 
447 
450 



453 
454 

457 



460 
461 
466 



468 

469 
470 

471 

475 
475 
476 
478 
481 
481 



489 
490 
493 



Safety from capsizing K. Wendel 496 

Capsizing "497 

Dimensioning of righting levers .... 497 

Specification of moments 498 

The righting levers 500 

Alterations of the righting levers due to wave* . . 500 

Safety allowance 501 

Stability criteria 502 

Measuring stability 503 



SAFETY AT SEA 
Cannes of accidents 

Investigation by model 



W. C. Miller 



505 
506 
507 



F**mmmmi4t*^ mf I mm*, 
OnSMUum OT tCB OH) 

Head to wind 
Wind 30 on the bow 
Stern to wind 
General comment 



DISCUSSION SEA BEHAVIOUR 
Small boat resistance 
Influence of nozzles 
Bulbous bows 

Statistical analysis of resistance 
Fishing gear resistance . 
Sea behaviour theory 
Observations of behaviour at sea 
Model tests in waves 
General design 
Authors* replies 
The Chair's summing up . 
Stability .... 
Safety at sea . 



H.Lackenby 



311 

513 
513 
513 
513 



515 
522 
530 
535 
540 
540 
542 
546 
555 
559 
567 
569 
578 



I PART IV PRODUCTIVITY | 

SYMPOSIUM OF BOAT TYPES 

SHORT DISTANCE FISHING 
Development of a boat for India's surf coasts 

P. Gurtner 
Surf conditions ....... 

Development first phase ..... 

Conclusions from first experiments .... 

Development second phase ..... 

Experiences from the tests with BB-57 

Prototype 1958 BB-58 ...... 

Future work mass production of BB-59 . 

Commercial outboard fishing craft D. D. Beach 
Florida mullet gillnet skiff ..... 

River gillnet tender ...... 

Oyster garvcy ....... 

Salmon net tender ....... 

New England lobster boat ..... 

Salmon trolling dories ...... 

Trap-net boats and harpoon boats 

V. Foderd, R. Sard and A. Cambiano 
Tuna trap-net boats . ..... 

Swordfish (Xiphias Radius) harpoon boats . 

MEDIUM DISTANCE FISHING 



General arrangement 

New trawling gear 

Production 

Engine output and cruising range 

Construction materials 

Crew's comfort . 

Mass production 

Cost and finance 

economics .... 



L. C. Ringhaver 



585 
586 
587 
588 
589 
592 
594 
595 

597 
597 
598 
599 
601 
607 
607 



609 
609 
611 



615 
615 
617 
618 
618 
619 
620 
620 
622 
623 



[8] 



CONTENTS 



Page 

No. 

PRODUCTIVITY SYMPOSIUM OF BOAT TYPES- 
MEDIUM DISTANCE FISHING (continued) 

of a trawKf of vKNrtho4ox design 

. C. B. Corlett andJ. Venus 624 

625 

Conttruction and operation 627 

Licensed building 629 

Future developments 629 



The Netherlands post-war fishing fleet 

P. Boogaard 

Shrimp trawler 

Motor cutter 

Trawler-drifter 

Trawler 



LONG DISTANCE FISHING 

Design studies for stern trawlers . H. Heinsohn 
Influence of the length of the gear .... 
Manoeuvring of the ship during hauling and shooting 

Fish holds and fish landing 

Transport of fish from stern to hold .... 

Fish meal plant 

Complement and accommodation .... 
Lifcsaving appliances . ... 

Classification and freeboard 

Choice of main engines 

Lines and stability 

Trawl winches .... 

Heinrich Meins 

CarlKtimpf 

Sagitta 

Performance 



French deep-sea salt cod trawlers 

Introduction of diesel propulsion 
Modern trawlers 
Cargo capacity and stability 
Short description of typical vessels 



E. R. Gueroult 



Diesel whale catchers . 

Increase of boat size and speed 
New devices on catchers .... 
Example of a modern Japanese diesel catcher 
Comparison of diesel and steam propulsion 



S. Takahashi 



631 
632 
633 
634 
636 



638 
638 
639 
639 
639 
639 
639 
639 
639 
640 
641 
643 
645 
645 
647 
647 

654 
654 
655 
656 
658 

661 
662 
663 
664 
666 



DISCUSSION BOAT TYPES 

Surf boats 

Short distance fishing .... 
Medium distance fishing .... 
Long distance fishing .... 

CHOICE OF SIZE AND TYPE 
Choice of boat type and size for Polish 

fisheries /. Swiecicki 

Aims of study 

Subject of study 

Range of study 

Method of choosing the optimum fishing boat . 
General results 



Propulsion and processing machinery for deep-sea 

trawlers C. C Eddie 

Types of machinery 

Design of diesel-electric equipment .... 

Economics of speed 

Economics of preservation 



No. 

668 
673 
688 
701 



708 
709 
709 
709 
710 
714 



715 
716 
717 
718 
720 



Modern factory ships in Japan 

S. Sato 723 

Basic design 725 

Fishing operations 726 

Selection of types 726 

Size of ships 727 

Fuel and freshwater 729 

Arrangement of factories 729 

Conveyors 729 

Refrigerating machinery 73 1 

Freezing equipment 731 

Cooling equipment for refrigeration of cargo holds 732 

Insulation 732 

Canning systems ....... 734 



DISCUSSION PRODUCTIVITY 

Choice of size and type 735 

Fishing boat of 1975 752 

REFERENCES 761 

INDEX 771 



ADVERTISEMENT SECTION 

At the end of this volume appears an advertisement section. This is included 
because it is appreciated that practical commercial information should be 
readily available for all interested parties, concerning fishing gear and equipment 
that can be procured from various sources for the betterment of fishing practices. 

The advertisements cover many pages and a complete index of the firms 
represented appears at the commencement of the section. 



[9] 



LIST OF CONTRIBUTORS 



Page 
No. 

AKASAKA, M 303 

President, Akasaka Iron Works Co. Ltd., 3, 1-chomc, Ginza, 
Chuo-ku, Tokyo, Japan. 



ALVERSON, D. L. 



101, 128, 133 



Chief, North Pacific Fisheries Exploration and Gear Research, 
UJS. Fish and Wildlife Service, Seattle, Washington, U.S.A. 



ARCOULIS, E. 



249 



Managing Director and Project Engineer, Evangelistria Com- 
pany, Bouboulina 2, Piraeus, Greece. 



BARDARSON, H. R. 



Naval Architect and Civil Engineer, Director of Iceland Govern- 
ment Inspection of Shipping, P.O. Box 61, Reykjavik, Iceland. 



BEACH, D. D. . 



597 



Naval Architect, 3813 South Sheridan Ave., Minneapolis 10, 
Minnesota, U.S.A. 



BEAUDOUX, E. . 



97, 308 



Directeur General adjoint, Ateliers et Chantiers de la Manchc, 
rue Charles Bloud, Dieppe (S.M.), France. 



BENFORD, PROFESSOR H. . 



320, 338 



Department of Naval Architecture and Marine Engineering, 
University of Michigan, Ann Arbor, Michigan, U.S.A. 

BIRKHOFF, C 102, 748, 749 

Dip]. Ing., Rickmers Werft, Bremenhaven, Germany. 



BOOGAARD, P. . 



. 631 



Chief, Shipping Department, Ministry of the Building Industry, 
Rotterdam, Netherlands. 

BoRDOLi, Dr. Ing. G 182 

Ingegnere Navalc c Mcccanico, Via Sistina 4, Rome. 

BULLJS, H. R 99 

Chief, Gulf Fisheries Exploration and Gear Research, U.S. Fish 
and Wildlife Service, Pascagoula, Mississippi, U.S.A. 

CAMBIANO, A 609 

Architetto Navale, Institute Nautico, Palermo, Sicily, Italy. 

CARDOSO, J. C. E 123,182 

Merchant Marine Inspector General, Ministry of Marine, 
"Boa Esperanza", Rua 9 de Abril, S. Pedro do Estoril, Portugal. 

CARVER, DR. E., Jr 541 

Naval Architect, Ocean Resources Institute Inc., Woods Hole, 
Massachusetts, U.S.A. 



CATASTA, L. 



Page 

No. 
. 198 



Costruttore Navale, Monte S. Michele, S. Benedetto del Tronto, 
Italy. 

CHAPELLE, H. I. . 96, 167, 169, 460, 516, 519, 566, 

671, 682, 736 

Curator, Division of Transportation, Smithsonian Institution, 
U.S. National Museum, Washington 25, D.C., U.S.A. 



CHARDOME, A. . 



. 289, 317 



Civil Engineer and Manager, Beliard, Crighton and Co., Ostend, 
Belgium. 



123, 179, 303, 578, 690 CHARDOME, P. . 



. 525 



Managing Director, Chantier Naval de Rupelmonde, Rupel- 
monde, Belgium. 

CHIGUSA, S 234 

Director, Nissin Kogyo Co. Ltd., Asahi Building, 3, 3-chome, 
Nakanoshima, Kha-ku, Osaka, Japan. 



CLAVEAU, J-M. 



97,98 



Directeur, Chantiers Navals Krebs, Concarneau (Finistere), 
France. 



COLVIN, T. E. . 



64 



Naval Architect, 1303 North Sheridan Road, Waukegan, 
Illinois, U.S.A. 



CORLETT, E. C. B., Ph.D. . 



627, 695, 698 



Managing Director, Burness, Corlett and Partners Ltd., Naval 
Architects and Marine Consultants, Worthing and London, 
England, U.K. 



COSTA, Capitano W. 



. 253 



Societa Gcnepesca Ufficio Tecnico, Viale L. da Vinci 45, 
Leghorn, Italy. 



CREWE, P. R. 



. 540 



Chief Engineer (Hydrodynamics), Saunders-Roe Ltd., Head 
Offices, Osborne, East Cowes, Isle of Wight, England, U.K. 

CRISTIANI, L 578 

Ingegnere Navale, 23 Via Francesco Crispi,' Rome. 

CROSIO, E. .' 197 

Vice-Dircttore Tecnologico, Pirelli S.p.A., Viale Abmzzi no. 94, 
Milan, Italy. 

CSUPOR, Dr. Ing. D. 531 

Maierform S.A., 29 rue du Rh6ne, Geneva, Switzerland. 

DE LASZLO, P. D 188, 198 

Director, Halmatic Ltd., 10 Upper Berkeley St., London, W.I. 



[11] 



LIST OF CONTRIBUTORS 



No. 
. , 56,95,96,123,197,581 

Deputy Inspector of Shipping 23 Dokweg, Ijmuiden, Nether- 
lands. 



08 WIT, J, G. . 



DlCKSON, W. . 



96, 388, 561 



Senior Scientific Officer, Marine Laboratory, Aberdeen, Scotland, 



DlLNOT, P. F. . 



Stone Marine Engineering Co. Ltd., Woolwich Road, Charlton, 
London, SJB.7. 



DOKB, C. 



Director, Miho Shipyard Co. Ltd., 7, 3-chome, Yaesu, Chuo-ku, 
Tokyo, Japan. 

DORVILLE, F 125 

MacOregor Comarain S.A. % bis, me du Ranelagh, Paris 16c 

Dousr, D. J. . . . 370,445,561,695,746 

Naval Architect, Ship Division, National Physical Laboratory, 
Fettham, Middlesex, England, U.K. 

DREOSTI, DR. G. M 239, 258 

Director, Fishing Industry Research Institute, University of 
Cape Town, Rondebosch, Cape Town, South Africa. 



DU CANE, Commander P. 



541,542,547,576 



Managing Director, Vosper Ltd., P.O. Box No. 18, Portsmouth, 
England, U.K. 



DUTRUIT, M. . 



. 579 



Safety Engineer, 3M Company of St. Paul, Minnesota, 7 Acacias, 
Prtlly, Vaud, Switzerland. 

EDDIE, G. C. . . 124, 134, 242, 247, 715, 750, 751 

Principal Scientific Officer, Department of Scientific and Indus- 
trial Research, Torry Research Station, Aberdeen, Scotland, U.K. 

EDGE, Captain, P. F 134,556 

Manager, Ross Trawlers Ltd., 1 Hutton Road, Orimsby, 
Lincolnshire, England, U.K. 



ESTEVE, V. 



99, 124 



Arquitecto Naval, Sindicato National de la Pesca, Paseo del 
Prado, Madrid, Spain. 



FEA, E. . 



. 196 



Ingegnere Navale e Meccanico, Centra Industrial e Navak, 
Via Ferdinando di Savoia 3, Rome. 



FINN, D. B., Ph.D., C.M.G. 
Director, Fisheries Division, FAO, Rome. 

FLINDT, R. I 



21 



. 304 



General Manager, Lister Blackstone Marine Ltd., Long Street, 
Dursley, Gloucestershire, England, U.K. 

FODERA, Dr. V 609 

Direttott, Centre Sperimentale Pesca, Palermo, Sicily, Italy. 



FUJINAMI, N . . 



Naval Architect, Fishing Boat Section, Fisheries Division, FAO, 
Rome. 



No. 

GARDNER,! 515,557,673 

Technical Editor, Maine Coast Fisherman, 33 Glen Park A venue, 
Saugus, Mass., U.SA. 

GIANESI, Don. Ing. G 249 

Ingegnere Refirigetmzkme, Samifi Milan, Via Clerici 7, Milan, 
Italy, 



741 GILLMER, Professor T. C. 



. 341 



Department of Marine Engineering, U.S. Naval Academy, 
Annapolis, Maryland, U.S.A. 



. 234 GOLDSWORTHY, E. C. 



. 124, 134 



Messrs. E. C. Goldsworthy, Estate Buildings, South Road, 
Weybridge, Surrey, England, U.K. 

GOPINATHA PILLAI, Dr. K. . . . .671 

Director of Fisheries, Trivandrum, Kerala, India. 

GNANADOSS, D. A. S 171,672 

Assistant Director of Fisheries, B-33, Chidambara Nagar, 
Tuticorin, India. 



GREENHILL, W. A. . 



. 303 



Managing Director, The Bergius Co. Ltd., 254 Debbie's Loan, 
Glasgow, C.4, Scotland, U.K. 

GUEROULT, E. R 654 

Architecte Naval, 26 rue Danielle Casanova, Paris 2c, 



GURTNER, P. . 



133, 585, 672 



Naval Architect, Fishing Boat Section, Fisheries Division, FAO, 
Rome. 

GUTSCHE, Dr. Ing. F ...... 522 

Lttcknitzstrasse 13, Friedrichshagen, Berlin, Germany. 



HAMLIN, C 
Naval Architect, Manset, Maine, U.S. A. 



172, 333 



HANSON, H. C. . . 101, 137, 167, 185, 332, 574 

Naval Architect and Marine Engineer, 102, Pier 52, Seattle 4, 
Wash., U.S.A. 

HANSSON, Captain H ..... 574, 579 
Director, Swedish Sea Rescue Institution, Gothenburg, Sweden 

HARDY, Commander A. C., 23, 27, 1 14 

39/41 New Broad Street, London, E.C.2. 

HARPER Gow, L. M., MJB.E. . . . 126,748 

Shipowner, Chr. Saivesen and Co., 29 Bernard Street, Edinburgh 
6, Scotland, U.K. 

HEEN, Dr. E ........ 239 

Chief, Technology Branch, Fisheries Division, FAO, Rome. 



HEINSOHN, H. 



. 123, 126, 134, 249, 638, 703 



DipL Ing., Rickroeri Waft, Pottfach 2066, Brcmerhaven 2 
Germany. 



. 536 HENICHICE, W. . 



184, 534, 548 



Director, ScUffbou-Venuchunstett, StflhUnpr 11, Bedin- 
Korbhont, Germany. 



[12] 



LIST OF CONTRIBUTORS 



H0ISGAARD, J 



Pat* 
No. 

96,307,580 



Chief Engineer, A/S Hundested Motorfabrik, Skaraevej, 
Hundested, Denmark. 



HOLT,S. J 

Chief, Biology Branch, Fisheries Division, FAO, Rome. 



94 



HOPWOOD, G. 



274, 315 



Chief Engineer, Mirrtees, Bickerton and Day Ltd., Hazel Grove, 
near Stockport, Cheshire, England, U.K. 

HUNTER, A. .127, 132, 198, 303, 305, 336, 524, 535, 
536, 540, 543, 571, 692, 697, 701 

Managing Director, Cook, Welton and Gemmell Ltd., Grovehill, 
Beveriey, Yorkshire, England, U.K. 

HUSE, H. V 303 

Managing Director, Hydraulik A/S, Brattvag, Norway. 

HUTCHINSON, J. G 582 

Administrative Service, Department of Fisheries, Wellington 
Street, Ottawa, Canada. 



INAMURA, K. 



295 



Chief, Fishing Boat Section, Fisheries Agency; now Director, 
Japan Export Frozen Marine Products Inspectorate Corporation, 
c/o Kohan Building No. 3, 3-Chome, Kasumigaseki Chiyoda-Ku, 
Tokyo, Japan. 



INKSTER, R. G., M.D. 



556 



Department of Anatomy, University New Buildings, Teviot 
Place, Edinburgh, Scotland, U.K. 

JABLONSKI, 468, 572 

Naval Architect, The Maritime Institute, Gdansk, Poland. 



JACOBSSON, Professor M. 



579 



Chairman,^ Swedish Sea Rescue Institution, Gothenburg, 
Sweden. 

JOHNSSON, N. V 530, 553 

Naval Architect, Nicolovinsgatan 8B, Malmo, Sweden. 

JOUDINSTEV, A. F 572, 750 

Engineer, U.S.S.R. Research Institute of Marine Fisheries and 
Oceanography (VNIRO), Verkhne Krosnoselskaja 17, Moscow, 
U.S.S.R. 



JUL, M. 



255, 752 



Director, Slagteriernes Fonkningsinstitut (The Danish Meat 
Research Institute), S0ndre Ringvej 16, Roskilde, Denmark. 



KANASASHI, Y. 



73,97 



President, Kanasashi Shipbuilding Co. Ltd., 4010-19, Mi ho, 
Shimizu City, Shizuoka Prefecture, Japan. 

KLAASSEN, H 305,524,580 

Chief Engineer, Lips Propeller Works, Drunen, Netherlands. 

KQBAYASHJ, T 146, 348 

Naval Architect, Fishing Boat Laboratory, Fisheries Agency, 
Tsiikishtma, Chuo-Kui, Tokyo, Japan. 



KOSSA, M. 



320, 338 



Naval Architect, Department of Naval Architecture and Marine 
Engineering, University of Michigan, Ann Arbor, Michigan, 

U.S.A. 



Page 
* tfo. 

KREUZBR, Dr. R ....... 239 

Chief, Fish Processing Section, Fisheries Division, FAO, Rome. 

KRISTJONSSON, H. . . .94, 97, 101, 128, 133 
Chief, Fishing Gear Section, Fisheries Division, FAO, Rome. 



KUMMERMAN, H 



748 



Pr6sident-Directeur Gtafari, MacGrcgor Comarain S.A., 
% bis, rue du Ranelagh, Paris 16c. 



LACHENAL, I. D 



676 



President, Inter-Island Deep-Sea Fishing Association, Navotas, 
Rizal, Philippines. 



LACKENBY, H. 



298, 364, 51 1, 535, 539, 694, 697 



Chief Naval Architect, The British Shipbuilding Research 
Association, 5 Chesterfield Gardens, Curzon Street, London, W.I . 



LEROUX, R. 



304 



Directeur, Societ6 Anonyme des Anciens Chantiers Dubigcon, 
1 Boulevard de Chantenay, Nantes (Loire-Inf(6rieure), France. 

LEWIS, Professor E. V. . . 535, 548, 554 

Head, Ship Division, Davidson Laboratory, Stevens Institute of 
Technology, 711 Hudson Street, Hoboken, New Jersey, U.S.A. 



LlNDBLOM, J 

Dipl. Ing., Oy Laivateollisuus Ab, Abo, Finland. 



182 



MACCALLUM, W. A. 



. 197, 208, 242, 258, 750 



Research Engineer, Fisheries Research Board of Canada, 
Technological Station, P.O. Box 429, Halifax, Nova Scotia, 
Canada. 



MCGRUER, E. 



179, 196, 557, 671 



Boatbuilding Officer, Scottish Country Industries Development 
Trust, 27 Walker Street, Edinburgh, Scotland, U.K. 



MALIC, J. B. 



676 



Fisheries Technician, Department of Agriculture and Natural 
Resources, Bureau of Fisheries, Manila, Philippines. 



MEWSE, H. V. N. 



274 



Marine Superintendent, J. Marr and Son Ltd., Fteetwood, 
Lancashire, England, U.K. 



MILLER, W. C. 



505 



Naval Architect and Marine Engineer, Wm. C. Miller and 
Associates, 577 Spreckles Building, San Diego 1, California, 
U.S.A. 



MILLER, W. P. . 



180, 556, 697 



Managing Director, James N. Miller and Sons Ltd., East Shore, 
St. Monance, Fife, Scotland, U.K. 



MILNE, G. S. 



124, 692, 750 



Shipyard General, Manager, John Lewis and Sons Ltd., 186 
Albert Quay, Aberdeen, Scotland, U.K. 



MlNOT, P. 



124, 541, 572, 755 



Naval Architect, Woods Hole Oceanographic Institution, 
Woods Hole, Mass., U.S.A. 

MITSUI, T 95, 197, 249, 347 

Chief of Hull Designing Section, Shimonoseki Works, Mit- 
subishi Shipbuilding and Engineering Co. Ltd., Enoura-1, 
Shimonoseki, Japan. 



113] 



LIST OF CONTRIBUTORS 



M5CKEL, Captain W. 



Pag* 

No. 

404,561 



Naval Architect, HamburgacbeSchiffbau-VmuchsanttaJt, Branv 
fettentrasse 164 (24), Hamburg 33, Germany. 



MURAMATSU, S. 



Chief, Design Section, Yaim Shipbuilding Co. Ltd., Yaizu City. 
Shtzuoka Prefecture, Japan. 



NlNOMIYA, M. , 



Fishing Boat Laboratory, Fisheries Agency, 1, 2 Kesumigeseki, 
Chiyoda-Ku, Tokyo, Japan. 



NUTKU, Professor A. 



517, 573, 675 



Department of Naval Architecture, Technical University, 
Istanbul, Turkey. 



O MEALLAIN, S. 



249, 336, 672, 750 



Chairman, Au fiord lascaigh Mhara; Inspector and Engineer, 
Fisheries Division, Department of Lands, 3 CathaJ Brugha 
Street, Dublin. 

ORSZULOK,W. . . . 95,308,741,750 

Naval Architect and Main Director, Central Design Office, 
United Polish Shipyards, Gdansk, Poland. 



Osn, O. 



253 



Ingegnere Refrigerazkme, Societa Ing. G. DeH'Orto, Via Meraao 
18, Milan, Italy. 



Otsu, Y. .... 

Chief, Fishing Boat Laboratory, Fisheries Agency, 1, 2 Kesumi- 
geseki, Chiyoda-Ku, Tokyo, Japan. 



PAIN, Commander H. E H. 



114, 134 



S. G. Brown Ltd., Shakespeare Street, Watford, Hertfordshire, 
England, UK. 

PA*KS, Sir Fred . . . 95, 123, 249, 3 

'Chairman and Managing Director, Boston Deep Sea Fisheries 
Ltd., 238 Dock Sttaet, Fleetwood, Lancashire, England, U.K. 



PAUL, D. A. 



693 



Naval Architect, Hall, Russell and Co. Ltd., 16 Carton Place, 
Aberdeen, Scotland, U.K. 



PAULUNG, Professor J. R., Jfc. , 



489, 574, 57T 



Department f Naval Architecture and Marine Engineering, 
University of California, Berkeley 4, California, USA. 

POPPER, F. E, .337 

Chief, Economic* Borneo* Fisheries Division, FAO, Rome, 



BROSKIE, J. 



. 94,122,242,332,519 



Oapaitment *f Fisheries, Ottawa^ Canasta. 

XL - ....*..,... JAp* 

Marine Sales Manager, Donald Macftesoa and Co. Ltd., 
27 Albion Street, Manchester 1 , Lancashire, Entfaad, (J .1C 



<JUKESHI, Dr. M. fl. 



674 



Binder, -Central Fisheries Department, Saddar, Karachi 3, 
ftekistan* 



RAHOLA, Professor 1 . . 
Aaetor 0f Hie Institute of Itttatftofy, Helsinki, Firifamd. 



571 



No. 
RANKCN, Commander M. B. F. 242, 255, 701, 741, 748, 752 

J. and E. Hall Ltd., Dartford Ironwork*, Dartford, Kent, 
England, U.K. 



84 RAPPINI, Don. Ing. G. 



309 



Direttore del Laboratorio, Ansaldo S.A., Piazza Carignano, 
Genoa, Italy. 



295 R*PSQN, Dr. A. M. 



Division of Fisheries, Department of Agriculture, Stock and 
Fisheries of the Papua and New Guinea Administration, Port 
Moresby, Papua, Australia. 



RASALAN, S. 6. 



676 



Chief, Division of Marine Fisheries, Bureau of Fisheries, Manila, 
Philippines. 

REAY^ Dr, G. A 200, 258 

Director, Department of Scientific and Industrial Research, 
Torry Research Station. Aberdeen, Scotland, U.K. 

REM0Y, Captain S. . . . 542, 570, 580, 581 
Government School of Fisheries, Fiord, Norway. 



REYES RISOTO, E. 



98 



Tecnico Naval, AMC. 335603, Apto. 2, c/56 and 58, Marianau. 
Habana, Cuba. 



146, 348, 550, 554 RUICEN ' H ' 



422 

Naval Architect Netherlands Ship Model Basin, Wageningen, 
Netherlands. 

RINGHAVER, L. C 615, 690 

President, Diesel Engine Sales Inc., St. Augustine, Florida, U.S.A. 



RODEN, S. 



576 



Naval Architect, Department of Naval Architecture, Technical 
University of Hamburg, Germany. 

ROSCHER,E. K 528 

Dipl. Ing., KttdienaJlee 57, Hamburg 1, Germany. 

SALOMON, H 308 

Manager, Svead s,i.a.s,, Via Montevideo 20, Rome. 

SANTARELUU M 684 

Iiigeniere Naval y Mecanico, Hip&lito Yrigoyen 723-4 Piso-of. 
31, Buenos Aires, Argentina. 



SARA, >ott. R 

Centro Sperimentale deUa Pesca, Patermo, Siciry, Italy. 



609 



SATO, S. 723 

Chief, Design Section, Hitachi Shipbuilding and Engineering Co. 
Ltd., Uuaoshsma Shipyard, iimoshiaia, Hiroshima Prefecture, 

lapan. 

SCHARFE, Dr. J 121, 125 

Gear Technologist, Fishing Gear Section, Fisheries Division, 
FAQ, Rome. 

SCHMIDT, R G., Jr. .... 31,128 

Pmttent, Marine Construction aad Design Co., 2100 Com- 
modore Way, Seattle 99, Wash., LLS.A. 



LIST OF CONTRIBUTORS 



Pag* 
No. 

SBGHERS,V 309 

Conitructeur-Armateur, Chantiers et Armement Seghen, Qua! 
du Slipway, 4, Ostend, Belgium, 



SEN, B, R. 

Director-General, FAO, Rome. 
SHEWAN, Dr. J. M. . 



200, 258 



Department of Scientific and Industrial Research, Torry Research 
Station, Aberdeen, Scotland. 



SICKLES, Lieut. -Commander C. M. 



581 



U.S. Coast Guard, O. in ., Merchant Marine Detail, c/o 
American Consulate General, Naples, Italy. 

SILVA, Commodore D. D. .... 242 

Chairman of "Commissfto Central das Pescarias", Member of 
the National FAO Committee, Rua D. Constantine Bracanca 10, 
Lisbon, Portugal. 

SIMPSON, D. S. 134, 152, 185, 304, 569, 581, 694, 745 

Naval Architect, 200 Summer Street, Boston 10, Massachusetts, 
U.S.A. 



SLAVIN, J. W. 



227, 247, 261, 745, 749 



Mechanical Engineer, Fishery Technological Laboratory, 
Division of Industrial Research and Services, U.S. Bureau of 
Commercial Fisheries, East Boston, Mass., U.S.A. 



SMITH, J. D. 



688 



Joe D. Smith and Associates, Consulting Engineers, 1202 
Graycroft Avenue, Madison, Tenn., U.S.A. 

SOUBLIN, L 124, 735 

President de la F6d6ration des Amateurs & la Peche de France, 
Qua! Guy de Maupassant, Fecamp (Seine-Maritime), France. 



STEEL, H. E., C.B.E. 



198, 576 



Director, Burness, Corlett and Partners Ltd., 41 St. Mary Axe, 
London, E.C.3. 



STRAKOSH, F 

Consulente navale, Via A. Rendano 18, Rome. 

STOKKE, I 



246 



Head, Department of Internal Combustion Engines, The 
Technical University of Norway, Trondheim, Norway. 

SVENKERUD, H 17 

Naval Architect, Fishing Boat Section, Fisheries Division, FAO, 
Rome; now A/S Nordisk Aluminium Industri, L0kkeveien 9, 
Oslo, Norway. 



SWIECICKI, J 

The Maritime Institute, Gdansk, Poland. 



708 



SWINFIBLD, A. N 169 

Naval Architect, 3OGrosvenor Street, Sydney, N.S.W., Australia. 

SUBERKRUB, F. 285 

Consulting Naval Architect, Chilehaus CVI, Hamburg 1, 
Germany. 

SUTHERLAND, A 180 

Senior Technical Officer, White Fish Authority, 5 Fortes Street, 
Edinburgh, Scotland, U.K. 



tot* 
No. 

96,175,475,576,577,754 
Department of Naval Architecture, Faculty of Engineering, 
University of Tokyo, Bunkyo-Ku, Tokyo, Japan, 



TAKAGI, Professor A. 



19 TAKAHASHI, S. 



126, 303, 661, 750 



Executive Director, Hayashikane Shipbuilding Co. Ltd., 
Shimonoteki, Japan. 



TANIGUCHI, K. 



453 



Chief, Nagasaki Experimental Tank Laboratory. Mitsubishi 
Shipbuilding and Engineering Co. Ltd., Nagasaki, Japan. 

THIBERGE, F 573 

Ingenieur, Bureau Veritas, Rue Henri Rochefort 31, Paris 17e. 

TlTO, J. M 671 

European Representative, Outboard Marine International S.A. 
of Nassau, Bahamas; Bruges, Belgium. 

TODD, Dr. F. H. . . . 304,542,543,548 

Superintendent, Ship Division, National Physical Laboratory 
Feltham, Middlesex, England, U.K. 



TOTHILL, J. T. 



353, 555, 559 



Naval Architect, Ship Laboratory, National Research Council, 
Ottawa, Canada. 



TOWLE, E. L. N. 



743 



Assistant Chief Engineer, Industrial and Marine Division, Motor 
Engineering Department, Metropolitan-Vickers Electrical Co. 
Ltd., Trafford Park, Manchester, England, U.K. 

TRAUNG, J-O. . 98, 133, 167, 183, 196, 428, 546, 562, 

575, 582, 673, 690, 755 
Chief, Fishing Boat Section, Fisheries Division, FAO, Rome. 



TSUCHIYA, T. 



542 



Naval Architect, Fishing Boat Laboratory, Fisheries Agency, 
Tsukishima, Chuo-Ku, Tokyo, Japan. 



TYRRELL, J. 



99, 176, 540, 542, 555 



Managing Director, John Tyrrell and Sons Ltd., South Quay, 
Aridow, Co. Wicklow, Ireland. 



261, 313 VAN MANEN, Dr. J. D. 



422,562 



Under-Director, Netherlands Ship Model Basin, 
Netherlands. . 

VARRIALE, L 
Ingegnere, Socteta Ansaldo, Genoa, Italy. 



307 



VENUS, J 



101, 198, 624, 695, 698 



Managing Director, Seawork Ltd., 41 St. Mary Axe, 
E.C.3. 



VOLKBR, Professor Dr. Ing. H ..... 337 

fnstitut fttr SchhTstechnik der Tedmiachen Hochschufe, Gun* 
hausstrasse 25, Vienna IV, Austria. 

VON BRANDT, Professor Dr. A. . . 102, 122, 133 

Direktor, Institut fur Net*- und Materialforschimg, Neuer 
Wall 72, Hamburg 36, Germany. 



VOSSERS, G. 
Head, 



393, 422, 555, 561 
Laboratory. Netherlands Ship Mwfel 



[15] 



LIST OF CONTRIBUTORS 

No. ffo. 

WBNBLUM, Professor Dr.-Ing. G. P. ZHWER, P. B ...... ITS, 668, 750 

515, 535, 540, 547, 567, 569 Nvtl Afcbittct, Tingjtuvtden 26, Otto. Norwy. 



Hunburg, Garmuty. 
WENDEL, Professor Dr.-Ing, K. . . . 491,577 ZIMMER, H. K ....... 178 

Head, Department of Naval Architecture, Technical Univmtty Naval Architect, Poetboks 1 130, Bcreen, Norway. 

of Hannover, and Frofesaor at the University of Hamburg, 
Stubbenhuk 10, Hamburg 11. Germany. 

YOKOYAMA,N ..... 146,348 ZWOLSMAN, W. . . . 185,334,418,524 
Naval Architect, Fishing Boat Laboratory, Fisheries Agency, Naval Architect, Holland Launch H.V., Zuidcujk 218, Zaandanf, 

Tsukishima, Chuo-Ku, Tokyo, Japan. Netherlands. 



[16] 



NOMENCLATURE AND SYMBOLS" 



A. TECHNICAL TERMS 



A * Lateral area of ship's profile, including erections, I* 

exposed to wind It 

Ab - Blade jua, developed (to shaft centre) 1HP 

A<i Blade area, developed (outside boss) J 

A ** Blade area, expanded 1C 

Am Midship section area 

A P - Blade area, projected (outside boss) 

A w = Waterplane area Kq 

AC <= Alternating current K t 

AP - Aft perpendicular KB 

B = Breadth or beam in water line; Centre of buoyancy KG 

BAR = Blade area ratio (outside boss) KG 

BG = Height, centre of gravity above centre of buoyancy 

BHP = Brake horsepower KG, 

BM = Height, mctaccntre above centre of buoyancy 

BMi Height, longitudinal mctaccntre above centre of KM 

buoyancy KMi 

BMi = Height, transverse mctaccntre above centre of KM t 

buoyancy k 

b = Centre of buoyancy of thin layer of fluid kj 

C, = Admiralty constant (Resistance) k t 

C s -- Admiralty constant (Self-propulsion) L 

& = Resistance constant (Froudc's circular C) L 

Cb - Block coefficient, also S L c 

C m = Midship area coefficient, also p L p 

C p Prismatic coefficient, also 9 L r 

C r = Residuary resistance coefficient LBP 

C w = Waterplane area coefficient, also a LCB 

CB r= Centre of buoyancy LCF 

CG = Centre of gravity LCG 

CN =- Cubic number LOA - 

CP = Controllable-pitch propeller 1 

c -= Speed of waves; Chord length of propeller at 0.7 R M 

D - Depth; Propeller diameter M h 

Ob Diameter of boss at rake line M t 

DAR = Disc area ratio (to shaft centre) 

DC = Direct current M w 

DHP * Deliver^ horsepower to propeller M^ 

d --= Draught, also T; Distance between centre of wind 

pressure and centre of water pressure MCT 1 in 

EHP Effective horsepower (tow rope horsepower from m 

resistance tests) N := 

F p " = Pitch acceleration at FP n 

FP - Forward perpendicular P 

f Freeboard P<i 

G Centre of gravity; Girth amidships P e 

GM - Height, me taccn trie P m 

GM| = Height, longitudinal metacentric P t 

GMt Height, transverse metacentric PC 

GZ Stability lever Pe 

GZ h Heeling lever Q 

GZ r Righting lever QPC 

g * Acceleration due to gravity R 

h ** Distance from centre of roll to crew's position ; Rf 

Wave amplitude Rr 

h w Hei^trfwave Rt = 

1 - Moment of inertia S 



Longitudinal moment of inertia of watcrpiane 

Transverse moment of inertia of waterplane 

Indicated horsepower 

Advance number 

Keel, at midship section 

- Speed Displacement constant (Froude's circu- 
lar K) 

Torque coefficient 

Thrust coefficient 

Height, centre of buoyancy above keel 

Height, centre of gravity above keel 

Maximum height of centre of gravity above keel 
from operational conditions 

Maximum height of centre of gravity above keel 
considering stability criteria 

Height, mctacentrc above keel 

Height, longitudinal mctacentrc above keel 

Height, transverse mctaccntre above keel 

Radius of gyration; Wave number 

Longitudinal radius of gyration 

Transverse radius of gyration 

Length in waterltne 

Length between perpendiculars, also LBP 

Length of entrance 

Length of parallel middle body 

Length of run 

Length between perpendiculars, also 

Longitudinal centre of buoyancy 

Longitudinal centre of flotation 

Longitudinal centre of gravity 

Length overall 

Any length defined in particular 

Metaccntrc 

Heeling moment 

Heeling moment due to centrifugal forces when 
turning 

Heeling moment due to wind forces 

Intersection of line of action of buoyancy and 
centreline, at an angle of heel 9 

Moment to change trim one inch 

Mass; coefficient 

Revolutions per minute 

Revolutions per second 

Pitch propeller; Trawl pull 

Pitch propeller (boss) 

Pitch propeller, mean effective 

Pitch propeller, mem (face) 

Pitch, propeller tip 

Propulsive coefficient 

Mean effective pressure 

Torque 

Quasi propulsive coefficient 

Radius, propeller; Resistance 

Resistance, frictional 

Resistance, residuary 

Resistance, total 

Surface, wetted , 



Compiled by H. Sventeud 
{17) 



NOMENCLATURES AND SYMBOLS 
A. TECHNICAL 



() * Wctted-surface constant (Froude's circular S) 

SHP - Shaft horse power 

T Draught, also d; Thrust; Juried; Temperature 

T* =- Draught at after perpendicular 

T * Boriod Of encounter 

Tr = Draught at forward perpendicular 

TI > Draught, loaded 

To -= Draught, light 

T p Period of pitch 

T r - Period of roll 

T z = Period of heave 

TFI Terns per inch immersion 

t Thrust deduction fraction; Thiclraess at shaft axis 

t r Cylindrical thickness at root 

U = Resultant inflow velocity at 0.7 R 

V Speed in knots 

V. = Speed of advance of propeller (knots) 

V w - Speed, wind 

VP Variable pitch propeller 

v ** Speed in ft./scc. (m./sec.) 

Wf = Wake fraction (Froude) 

w t = Wake fraction (Taylor) 

y = Horizontal shift of centre of gravity of fluid 

Z = Heave amplitude; Section modulus 

z Vertical shift of centre of gravity of fluid 

a = Waterplane area coefficient, also C*; Wave 

direction 

e = Waterplane entrance coefficient 

i Angle of nozzle profile relative to shaft line 

^Oe = Half angle of entrance 

P =* Midship area coefficient, also C m 

y = Displacement, volume of in cubic metres 

y =n Displacement, volume of in cubic feet 



A - DispUooncmt, weight of in metric ton; Small 

increment (e.g. A SHP) 

A, - Displacement, weight of in long tons 

AKt n Thrust increase coefficient 

AT = Thrust increase 

o ma Block coefRcient, also Cb 

c = Phase angje 

Cw = Wind pressure coefficient 

TI = Efficiency 

i7b = Efficiency, propeller behind ship 

i^h = Efficiency, hull 

170 Efficiency* propeller in open 

r] p = Efficiency, propulsive 

??r = Efficiency, relative rotative 

= Efficiency, rest 

= Efficiency, trawling 

Wave direction 

A = Tuning factor 

AP ** Tuning factor, pitch 

y^ z = Tuning factor, heave 

x - Wave length; Coefficient of heat conductivity 

JJL Wave frequency 

I'm Maximum wave slope 

p = Density (mass per unit volume) 

pi = Density of air 

9 - Prismatic coefficient, also Q>; Angle of roll 

? e = Prismatic coefficient, entrance 

9r = Prismatic coefficient run ; Range of angles of heel 

giving positive righting levers 

9s = Angle of heel of maximum righting lever 

X = Yawing 

y> = Angle of pitch 

<o -= Angular velocity; frequency 

d> r = Natural frequency 



A = Ampere(s) 

BTU = British thermal unit(s) 

C Degree(s) Centigrade 

cal. Cakme(s) 

cm. = Centimetre(s) 

c.p.m. == Cycles per minute 

c.p.s. Cycles per second 

cu. Cubic 

F = Degree(s) Fahrenheit 

fm. = Fathom(s) 

ft. -B Foot or Feet 

GT = Gross tonnage 

g. = Gramme(s) 

gal. =- U.S. gallon(s) 



cyl. 
diam. 

% 
mid. 



B. MEASUREMENTS 

h.p. == Horsepower(s) NT 

hr. = Hour(s) 2 - 

Imp. gal. Imperial gallon(s) RT 

in. = Inch(es) rad. 

kcal. -- Kilocaloric(s) r.p.m. 

kg. Kilogramme(s) r.p.s. 

km. = Kilometre(s) sec. 

kW - Kilowatt(s) sq. 

I. Litre(s) ton 

Ib, -= Pound(s), avoirdupois 

m. -= Metre(s) 

min. = Minute(s) 

ml. . Millilitre(s) tons 

mm. = Millimctre<s) V 

W 



C ABBREVIATIONS 



Cylinders) 
Diameter 
Figures) 
Moulded 



P- 
pp. 
vol. 
wt. 



- Page 
=^ Pages 
*= Volume 



Net tonnage 

Ounce(s), avoirdupois 

Tons of refrigeration 

Radians) 

Revolutions per minute 

Revolutions per second 

SeconoXs) 

Square 

Metric ton(s)- 1,000 kg. 

=2,204 Ib. avoirdupois 

-0.984 long ton 

-1.102 short ton 

Long ton(s) (British) 

Volt(s) 

Watt(s) 



This ttst |i bated on BSRA'i Standard Nomcndauirc and Symbols (1949), but hat abo been partly influenced 
ITIXTi 1951 recommendations. Under no circumstances must it be interpreted t an officUl FAO tuggwtkm, ai it 

ITTC wffl achieve internattooal agreement on naval ai^hecturc mnnendature, 

f!8J 



^y indiyidttal ittafe a 
ihoped^TtinlWthe 



PREFACE 

* | ^HE Second FAO World Fishing Boat Congress, held in Rome from 5 to 10 April, 1959, provided 
1 an inspiring example of international co-operation, and the generous response in attendance and 
JL technical contributions showed clearly the importance now attached by governments to fishing 

boat design in the wider context of over-all efficiency of the fishing industry, safety of fishermen at se* 

and advancement of human nutrition. 

FAO has been the spearhead of much pioneering work in the improvement of production techniques 
in agriculture, forestry and fishery, and this Congress was among the most fruitful it has initiated* The 
Congress illustrated one of the methods FAO uses to secure the exchange of ideas and to disseminate 
information. It did not come about in an ad hoc manner. It was a carefully prepared part of a very 
much larger plan of attack on one of the most crucial problems that face the world: that of increasing 
food production, particularly animal protein foods, to meet the demands of a world population which 
is increasing at a fast rate. The population of the world today is about 2,800 million, and is increasing 
at the average rate of 1 .6 per cent, per annum. According to a recent United Nations survey, it has been 
estimated that the world population might double itself by the end of this century. This will undoubtedly 
exert a tremendous strain on the world's food resources. Even to maintain the current unsatisfactory 
levels of nutrition, special efforts will be needed to increase agricultural and industrial production. One 
source which may make a notable contribution to world food supplies is the inland water and oceans. 
These waters cover about seven-tenths of the world's surface, and produce mostly animal protein food, 
but at the present time not more than 1 per cent, of the food consumed by human beings is derived from 
this source. The importance of scientific and technical developments to increase man's ability to 
utilize the resources of the sea can, therefore, be easily realized. Compared with farming, fishing still 
remains more of a hunting operation. It is not difficult to see that as husbandry gradually takes the place 
of hunting, the oceans will yield larger harvests of fish, and, in tht< field, the work of the Fishing Boat 
Congress made, I am sure, a significant contribution. 

The fishing boat constitutes the heaviest part of investment in the fishing industries of highly developed 
countries, higher than the investment in harbours, canning plants and retail stores. A recent investiga- 
tion in Canada showed that vessels accounted for 67 per cent, of the total investment of the Canadian 
fishing industry, as against 45 per cent, in 1917, and 59 per cent, in 1935. This fact underlines the 
dominant position of fishing vessels in the economics of the fishing industry and how important is the 
need to increase their efficiency in the effort to catch more fish. Such an increase will not only add to 
the world's food supplies but will also increase the prosperity of the world's fishing industries, and raise 
the living standards of the fishermen. 

Awareness of the need to increase the efficiency of boats is reflected in the fact that more naval 
architects are being employed in the design and construction of fishing craft, and that professors of 
naval architecture and shipbuilding research organizations are starting to work on improving designs 
of fishing boats. The proceedings of the Congress, which are published in this volume, FISHING BOATS 
OF THE WORLD : 2, point to the trends and developments arising from this new interest. Technically, the 
book is both supplementary and complementary to volume No. 1 of the same title, based on the 

proceedings of the first Congress, and it will be, I feel, equally, if not more widely, welcomed. 



The first Congress in 1953 played an important pan in drawing the attention of governments to the 
contribution that naval architects could make to the efficiency and prosperity of fishing industries. 
Indeed, until a few years ago, government activity in the fishing industry was mainly in the hands of 
biologists. In 1950, when FAO first employed a naval architect, only the governments of Norway and 
Japan had established posts for naval architects. Hie situation has improved since then, and some 
other governments, such as those of India, Israel, Newfoundland and Turkey, have since employed 
naval architects. In Canada, France, Germany, U.K. and U.S.A*, naval architects have been employed 

[19] 



PREFACE 

in semi*government research institutions engaged in fishing boat development work, but, on the whole, 
naval architects are still the exception ratter than the rule hi national fishery administrations. But 
several governments are now considering the establishment of fishing boat departments to help promote 
the development of the fishing industry . 

In this respect there is much to encourage the hope that the resources of the seas and oceans, the 
lakes and rivers and other waters, can yield much more food for human consumption than is at present 
harvested from them. For example, in recent years experience has shown that pelagic fish, such as the 
tuna, may be caught over wide areas of the oceans and seas. The Japanese are making substantial 
catches of such species hi the South Atlantic, white French fishermen, operating from Dakar in West 
Africa, have built up a tuna fishing industry. Again, the Mediterranean is generally regarded as a 
poor fishing sea and until recently shrimp fishing was of little importance there. But, a few years ago, 
French fishermen discovered substantial stocks of big, excellent quality shrimp and, as a result, trawlers 
from Algeria, Egypt, Italy and Turkey are fishing these stocks. Another outstanding example has been 
the rapid development of the pilchard fishery in South Africa and the ansiovy fishery off Peru. Here 
are thriving fisheries which have been developed in a few years and have already yielded millions of 
tons of fish. 

I mention these few examples to indicate something of the huge potential of the sea. Marine biologists 
have concluded that it should be possible to increase the world commercial catch of fish from about 
30 to 60 million tons a year from existing known stocks. But, of course, if this is to be done then an 
essential development, among other things, is an improvement in fishing boat design and performance 
throughout the world and not only in a few of the more advanced countries. One of the most significant 
contributions made by the Second FAO World Fishing Boat Congress has been to help spread this 
knowledge internationally. 

While the Second FAO World Fishing Boat Congress was an important milestone, much remains to 
be done before fishing boat design as a whole reaches the technical level achieved in the design of other 
types of ships. The application of science and modern techniques to the improvement of agriculture 
has yielded highly beneficial results, both to the producer and the consumer. The same process could 
make the fishing boat more efficient, thereby producing more food for the world while bringing to the 
fishermen a higher standard of living. 

B. R. SEN 
Director-General of FAO 



120] 



INTRODUCTION 

IT has already been demonstrated how the ingenuity of mankind can reach out to space and the 
stars, an ingenuity we also need to turn earthwards towards the art of living. Imagination plays a 
great part in determining what the future holds. Before ever there was a wheel, somebody imagined 
what a wheel was like; before ever there was a sidewalk or pavement, somebody conceived the idea; 
before there was a sail or a steam engine, there was a dream on somebody's part, and so ideas always 
precede things. 

My collaborators, besides being practical, hard-headed technicians and scientists, also have this 
valuable gift of imagination. Some of them have put forward an idea which, at first sight, seems so 
fanciful as to be impossible that is to fish from submarines to escape the perils of weather and to 
increase fish catching efficiency. But progress in fish finding and in the capture of fish is so rapid that 
the adaptation of these techniques to submarine fishing has become largely a matter of applied 
engineering. Submarine fishing may seem impossible today, but I should not be at all surprised to see 
it in practice tomorrow. And perhaps this is another way in which atomic energy may be turned to 
peaceful uses. The application of ingenuity, founded on proper scientific and technical knowledge, 
leads to progress. 

Since the 1953 First Boat Congress there have been many new developments. Chilled sea water for 
preserving the catch is being introduced on the Pacific Coast of the Americas. Large powered blocks 
are being introduced to handle encircling nets. More fishing vessels are being built with transom sterns, 
and even bulbous bows are now used on large trawlers. Stern trawling is being adopted on large 
factory trawlers, and there have also been advances in the design of dicsel and free piston machinery, as 
well as in the design of propellers. Wooden hulls, as another example, are still built in different strengths 
in many countries. Standardization of scantlings and better methods of construction of such ships 
could lead to substantial economies. New materials, such as plastic, are being introduced and recently 
there has been much progress in our knowledge of the behaviour of ships in a seaway which could be 
applied to the design of fishing vessels. 

The fishing boat particularly that below 100 ft. (30 m.) is a much neglected sector of the fishing 
industry in spite of the fact that it has such a lot to do with the efficiency of fishing or fishing operations. 
It was, therefore, an encouraging experience to see that so many professional and technical men from 
many countries came, at their own expense, and contributed to the Second World Fishing Boat 
Congress* This fact in itself illustrates the awakening of world interest in fishing boat design, con- 
struction and performance. 

I would like first of all to thank those from outside FAO who, over the past six years, and more 
particularly in the last two years, gave unstintingly and freely of their time in organizing the Congress. 

It is very seldom that I have had the privilege of following a Congress which has been marked by 
harder work or such vigorous discussion, and I think that all who shared this experience feet that the 
meeting was a rewarding success. This can particularly be attributed to the following: 

The amount of preparation that went into the Congress 

Work on it was started in 1957 by the Secretariat, with the assistance of a Committee 

The high level of the papers 

The professional and technical competence of those attending, which was reflected in the 
discussions 

The very effective leadership of your Chairman, Commander A. C. Hardy (U.K.) and the 
Vice-Chairmen, Professor A. Takagi (Japan), Professor G. Weinbhim (Germany), M. E. R* 
Gueroult (Prance) and Mr H. C. Hanson (U.S.A.). I also want to mention Mr. J. G. de Wit 
(Netherlands). 

121 J 



INTRODUCTION 

I noted at this Congress the emphasis upon the human factor, on the people who have to go to sea. 
This is a factor of over-riding importance which has sometimes, in the past, been overlooked, but the 
meeting showed that the designers, engineers and managers of today are taking it fully into account* 

There was also the discussion on new materials and the adaptation of skills and of sciences that have 
been developed in shipbuilding, which showed not only awareness of present day scientific and technical 
advances but also an example of the use of imagination. 

No meeting of this kind can deal adequately with all the subjects in its field and, without doubt, 
many aspects of fishing boat design, construction and performance should have been treated in more 
detail. Personally, I feel still more attention should have been focussed on small vessels, craft which 
are only just beginning to receive attention from naval architects, technicians and engineers. Perhaps 
the theme of the 1965 Congress should be "Mechanised craft of less than 100 tons". 

The vast majority of fishing boats in the world are certainly of less than 100 tons, most of them, 
indeed, are of only a few tons but it is these numerous fleets of small boats plying their trade off the 
coasts of all the fishing countries of the world which have, in the past, been most neglected by the 
naval architect, boat designer and builder and engineer. Yet, paradoxically, these are the boats that are 
most likely to benefit from the attention of the scientist and engineer and this is one reason why I 
should like to see them be the centre of interest and attention at our next congress. 

To sum up, I think that this Congress pointed to the upward trend of the application of science, 
technology and engineering to fishing boats. Meetings of this kind are essential in encouraging progress 
in the world, and I doubt if there will ever come a time when it will not be necessary to exchange 
knowledge and opinions and exercise our imagination. The action, therefore, of the governing body of 
FAO in providing for these congresses at intervals of six years or thereabouts is a wise provision. 

D. B. FINN 
Director, Fisheries Division, FAO 



[22] 



NOTE FROM THE CHAIRMAN 

THE fishing boat is not only a large part of the investment in the fishing industry as a whole; 
we must also realize that each individual boat is costly. 40,000 or $100,000 is not too much 
money for a medium-sized fishing vessel. A modern British super-trawler costs 300,000, or 
$1,000,000, today, and most recent factory ships cost some 1,000,000, or $3,000,000. 

In view of the many hundreds of thousands of fishing boats in use under different weather conditions, 
in various areas, it should seem easy to ascertain from fishermen the hull shape to combine best sea 
behaviour with toast resistance. This is, unfortunately, not the case; it is virtually impossible to get 
reliable information from talking to fishermen because they mostly have too little experience of the sea 
behaviour of different boat types and sizes and they have a tendency to confuse their observations, The 
laws of naval architecture often fly in the face of common sense; a longer or a lighter boat will always 
be better in waves than a shorter one, even if non-dimensionally it is inferior; ballast sometimes makes 
a boat roll most uncomfortably. The fisherman has not always the knowledge necessary to separate 
such factors and might conclude that a longer boat is better due to its shape, when perhaps the reason 
is only the length. Furthermore, during his lifetime a fisherman usually sails only about a dozen boats, 
mostly from the one port, and of a similar type; so his experience on different boat types is normally 
very limited in contrast to his experience of catching fish. 

Nobody would think if designing a transatlantic liner of asking members of a crew to specify 
the design : this is based on research and a careful study of conditions, analysis of operating conditions 
and the co-ordination of technical and economic aspects. If fishing boats are to be improved, the same 
analytical approach is definitely necessary. Science must play as important a part in fishing as it has 
played in agriculture, forestry and nutrition. I think the time has come for naval architects to realize 
that if we wish to design better fishing boats we must operate very closely with all disciples of fisheries 
science. The term "fisheries science" is comparatively new, but it is probably the best way of describing 
the change from unplanned hunting to the organized utilization of the untapped resources of the sea. 

Therefore, at the Second FAO World Fishing Boat Congress we had not only naval architects; we 
had biologists, we had practical fishermen themselves, who gave their point of view. We also had very 
distinguished fishing boat owners and builders. And in a long experience of national and international 
conferences I have never been to one in which there was so much real friei illness. And furthermore, I 
feel this particularly as Chairman, I have never been to a conference whic was harder work, because 
the speed of discussion was really terrific. The volume of qut&tions was toi dntial. And in dealing with 
the matter from the Chair, it was rather like trying to turn off a shower in a bath-tub because you 
realized that you had only a certain amount of time to give to any particular subject. Some people were 
good; they talked slowly and deliberately, and they kept to the rules of the length of speaking. But others 
went on and on. But the trouble was that they weren't just talking. They were talking "good stuff"* 
So how possibly could you extract the maximum from it and let people feel that everybody was satisfied ? 

However we invited participants and those who had no opportunity to attend to expand their remarks 
in writing. This invitation has been acted upon to a very great extent and the 225-page discussion in 
this book probably constitutes somewhat of a record for a four days' technical meeting of this kind. 
Naturally some condensation has been necessary, but I am happy to note, as I did in my introduction 
to the first fishing boat book that "the opinions are presented as they have been expressed and just 
as often as they occur. No attempt is made to talk down to the reader or to tell him what he ought to 
do". This book has the thickness of a very large Bible and indeed, together with the first book, it will 
be a super-Bible for fishing boat builders and designers for a long time to cone. 

The Second FAO World Fishing Boat Congress was very worthwhile, and X would like to say quite 
definitely that nobody could have done this better than the appropriate United Nations body the 

[23] 



NOTE FROM THE CHAIRMAN 

FAO Fisheries Division. In organizing technical meetings one very easily totes one's sense of 
proportion but because this was an integral part of the activities of the FAO Fisheries Division, it had 
a very good balance. 

At the last Congress we did not dare to take you as far as atomic propulsion, but in the discussion 
on the 197S fishing boat Professor A. Takagi from Tokyo made some suggestions along these lines. 

Now, it means just this: that if the Japanese are right, and if they can produce these atomic ships, 
that the factory can stay at sea for maybe two years. Well, you'll say : that's ridiculous. What about the 
poor crew? I say: That's all right, don't worry about that. Undoubtedly, such a ship would have a 
flight deck. And every six months, or less, if necessary, crew A would be flown home and crew B would 
be flown out. And possibly too, the catch, the frozen packaged fillets of fish, would be flown away 
out of the freezing hold in the ship. So this ship might be fishing up in the north, and within 24 hours 
a freshly filleted, deep-frozen packaged piece of plaice or sole could be enjoyed by someone in Alice 
Town in the middle of Australia. This is not a flight of fancy, it is a distinct possibility, and I give it 
to you as an idea of the tremendous pace of life today. And as this book goes to press we have news of 
a proposal to use surplus aircraft carriers as mother- and/or factory-ships. The way in which the air 
is leading us by the nose, the whole tempo of life is being speeded up. It is time we did speed up the 
tempo of the fishing industry in view of the fact that only a fraction of 1 per cent, of the food we eat 
comes from the oceans and seas, although they cover more than 70 per cent, of the surface of the 
world some 90,000,000 square miles. Old style fishing is not good enough to-day. We have seen 
something of the new style in the factory ships and, for example, in the way Russia has built up great 
fishing fleets. We have also seen a new development in fishing in the way the Japanese have set up 
fishing enterprises in collaboration with governments of many countries, for example Israel, Ceylon 
and Brazil. All these efforts are directed towards solving one of the continuing problems of to-day, 
production and distribution of more and better food. 

Fishing thought of the world is going through a period of intense change in which we are taking the 
"maybe" and "could be" out of it, and making it into a hard science, realizing that "world fishing is 
world feeding* 9 . 

A. C. HARDY 



[24] 



PART I 
TACTICS 







A.C.Hanfy 27 PttbMiMwl , . 

9Q 



PISHING METHODS AND DECK ARRANGEMENT 

On* . - 94 



P.O. Scheldt, Jr. 31 TrwB: 

^-t *+ 

a v 



/. C. A PW 56 COMMAND r OPERATIONS 



T.E.Colvto 64 CMtwItai cnrinl f trawtav 

A.C.H~4ya*IH.E.B.P4* 114 

73 



PRINCIPAL FISHING BOAT TYPES 

by 

A. C. HARDY 

A table giving the world diitribution of the important types of fishing boats at a glance is given. It contains 1 7 basic types operated by 
44 fishing nations, catching between them 92,9 per cent of the world's fish. /FF 



LES PRINCIPALS TYPES DE NAVIRES DE PECHE 

A cet egard, on a pens* qu'un tableau dormant d'un seul coup d'oeil la distribution mondial* des types importants de navires de pecbe 
etait utile, Le tableau contient 17 types de base de navires employes par 44 nations pratiquant la peche et dont les prises reprfeentent 92,9 
pour cent des poissons peches dans le monde. 



PR1NCIPALES T1POS DE BARCOS DE PESCA 

Se da una tabla con la distribuci6n mundial de los tipos mis importantes de barcos de pesca. Contiene 17 tipos bisk 
en 44 naciones pesqueras que capturan cntrc ellas el 92,9% de la pesca mundial. 



nple.dc 



IT has been judged useful to prepare a basic table 
giving the principal ship or boat types used in fishing 
other than those for purely local and off-shore duty. 
Fig. 1 shows the distribution of the types among 48 
different areas and countries. In order to simplify 
matters, the types have not been rigidly analysed in so far 
as sub-types are concerned; rather has the basic function 
been chosen. The top of the table shows a total of 17 
individual types. The columns to the left show the 
principal fishing nations, divided into geographical areas 
and arranged in alphabetical order within the continental 
divisions. 

Grouping of boat types 

The first shown is the whale-catcher, a boat for shooting, 
usually attached to the whale factory ship, but capable of 
operating if necessary from shore bases. There are two 
kinds of factory ships: (1) the mother ship which operates 
with catchers and is concerned in processing or canning; 
(2) the fishing stern chute factory, a new type also coming 
into prominence particularly in the fishing fleets of the 
U.S.S.R. This type formed the subject of much debate, 
some of it acrimonious, on the occasion of the 1953 
Congress. It is now beginning to reach maturity, and is a 
completely self-contained type planned for gutting, pro- 
ducing fish meal, extracting liver oil, and for producing 
frozen fillets in packaged form ready for the consumer 
market* The port of discharge is not usually a conven- 
tional fishing port 

The next group is the trawler family and it is divided 
into distant water and near-middle water types. Then 
come its near relations, the Pareja, and Grand Banker 



trawlers. Seiners, both Danish and Purse, follow; then 
the large and diversified drift-net family. 

The angling boat group consists of (rollers, tuna 
clippers and longliners. The recent arrival in France of 
the U.S. type tuna clipper as opposed to the sail-driven 
trolling tunny ship of former years is to be noted; it 
represents a revolution in an important branch of the 
French fishing industry. Longliners can be adapted from 
other types, particularly in northern waters where a 
longliner can be employed as a trawler and vice-versa; 
they can also be specially built. In Japan and Canada 
longliners are one-purpose boats. The dory-type long- 
liner is confined to Portuguese and Canadian ownership. 
There is a column for the carrier, which sometimes carries 
fish in tanks with chilled seawater and on others in wells 
open to the sea. This is followed by research and training 
ships which are employed by no less than sixteen different 
nations, and this is an indication of the importance with 
which the training of fishermen and biological research 
is regarded. 

No attempt has been made to list hospital ships, 
accompanying the fleets at sea; there are a few of these, 
some acting as store ships too, and some adapted to trawl 
fishing. They are giainly owned by two nations, namely 
the Portuguese and the Dutch. There are also fisheries 
protection ships of the United Kingdom and Germany 
equipped with hospital facilities. 

Variety of type* within countries 
A study of fig. 1 produces many interesting facts. The 
catch figures of each national column are in some respect 
a measure of each nation's reliance on fishing as a means. 



(27) 



FISHING BOATS OF THE WORLD : 2 TACTICS 




Fig. 1. Table of fishing boat types 



of feeding, or for export purposes, or both. In this respect 
it is natural that Japan should lead in the variety of boats 
with a total of 14 individual types; followed by the 
ILS.S.R. with 11 and Norway with 10, though this figure 
is dependent on the inclusion of factory mothcrships. 
In point of fact, Norway was the first country in the world 
to adapt an ex-tank-landing ship, built during World 
War II, as a complete herring oil and meal floating factory 
working in conjunction with a group of catchers; in 1957 
this ship was offered for sale. U.S.A. has 9 different 
types. The United Kingdom, Canada and Iceland list a 
total of 7 ship types; Portugal, France, Sweden and India, 
6 each; the Faroes, Germany, the Netherlands and Italy 
5; Denmark, Eastern Germany, Indonesia and the Union 
of South Africa 4. 

A nation's interest in fishing, however, cannot be 
judged by the number of types it used, this is controlled 
by such factors as the size of the country and its internal 
needs, the fishing grounds which are within reasonable 
distance, and the extent to which fishing is an export 
industry, i.e. canning, salting, etc., rather than a means of 
national feeding. On size comparison it is noted that 
Japan uses 14 types compared with only 11 by the 
U.S.S.R. Other factors which affect fishing arc the size 
and type* of harbours; the size of population willing or 
aWe to go to sea in the fishing industry, and their expert- 
as sailors. The available fishing population is 



governed in some degree by the way in which other 
industries intrude, and the extent to which they can 
absorb labour. 

Change in appearance 

Seven decades of trawler evolution are outlined in fig. 2, 
which is a good example of the development of a fishing 
vessel type. It is a slow and gradual process, for deep-sea 
fishing is not a business which encourages the taking of 
unnecessary chances. 

The coming of steam for propulsion in the 1880*8 was 
perhaps the most important stage. The ever increasing 
length of voyages, due to fish movements and over-fishing, 
brought about an increase in size. The advent of oil as a 
fuel for boilers permitted even longer voyages, although 
its use was strongly resisted at first, particularly in Great 
Britain 

The internal combustion engine, just before the out- 
break of World War I, probably caused the biggest 
change which has ever affected shipping. It was not, 
however, until well after World War II that it began to 
affect the trawler. Even today steam has not entirely 
disappeared. The use of electricity for propulsion, and 
in certain instances for the whole powering of the ship, 
is however now slowly gaining acceptance. 

The growing importance of the bridge at the nerve 
centre has eliminated outside walkways and increased the 



(28) 




SAIL SMACE 1883 





90 ft. 1886 



101ft. 6in. 1803 




110ft. 1898 



112ft. 1910 



138ft. 4in. 1910 





140ft. 600 IBP 1924 



152ft. 650 IHP 1933 



180ft. 800 IHP 1934 




172ft. 950 IHP 1936 



178ft. 950 IHP 1939 





167ft. 950 IHP 1946 (First Oil Burner) DIESEL TRAWLER 137ft. 600 BHP 1948 




182ft. 1,000 IHP 1948 



185ft. 1,35O IHP 1951 




185ft. 1,350 IIP 1966 



185ft. 1,500 SHP 1907 



Fig. 2. Stvt*tkca4eseftrawk 



(29) 



FISHING BOATS OF THE WORLD i 2 TACTICS 



size of the structure itself. Alterations in machinery have 
progressively cot down the size of funnels. An entirely 
new type of funnel was introduced in 1946, a period 
which marked the virtual end of the tall stovepipe struc- 
ture previously necessary to obtain draught for the rather 
inefficient coal-fired boilers. 

Model testing led to a cruiser-conical type of stern 
about 1933. At the same time there was a tendency up to 
the outbreak of World War II to increase the sheer 
forward, rake the stem and build up the foVsle; this, 
for reasons of seaworthiness, was frequently of turtle- 
back type. The introduction of the cruiser-conical stern 
seemed to be the signal to increase the structure aft. 
This improved comfort, gave extra space for accommoda- 
tion and reduced the risk of the ship being pooped. Later 
the mizzen-mast was eliminated, although this is not a 
common characteristic. The present tendency to fish on 
the starboard side only enables the superstructure to be 
extended on the port side, again resulting in more and 
better accommodation, and better quarters for the crew. 



Common types of boat 

The figures at the bottom of the columns of fig. 1 show 
the extent to which various basic fishing boat types are 
used. It is evident that on present showing, i.e. April 
19S9, the trawler in one or other of its various forms is 



the most popular 35 nations use it Next oomes the 
drifter, which again in one or another of many forms is 
used by 29 nations. This is followed by the purte seiner 
employed by 26 nations, compared with the Danish type 
of seiner employed by only 8. Other high-ranking figures 
are the troller, shared by 12 nations, and the whale* 
catcher used by 11 this is employed by 5 nations as 
shore-based, as apart from the factory-based unit. The 
Pareja is shared by as many as 8; the research and 
training ship has a total of 16. The almost universal 
popularity of the trawler, of near and middle water type, 
is especially to be noted, and is in fact used by all North 
Atlantic, Baltic and Mediterranean nations. The Nether* 
lands has specialized in drifter type ships. 

The common characteristic, it should be emphasized, 
is merely one of method of fishing; in size, power, 
equipment, they vary according to local conditions and 
local sources of supply, or to the extent to which inter- 
national sources of supply can be called upon. 

It is felt that in the past all these factors for ship types 
shared by so many nations have been confined to national 
"watertight boxes". It is the object of this paper to 
break open the boxes and to let ideas mingle freely. 
Although there are clearly many points in design which 
could never be common to all, and perhaps only common 
to a few, the exchange of ideas cannot but be of benefit 
for all. 



(30) 



PURSE SEINING: DECK DESIGN AND EQUIPMENT 



\ 



by 
PETER G. SCHMIDT, Jr. 



More fith arc produced by pune seining, which is the most important form of encircle net fishing, than by any other bask method, 
and purse seine vessel design has improved rapidly in the last few years. The most important purse seining systems are the two-boat system, 
as used in the Norwegian herring fishery and the U.S. East Coast menhaden fishery, and the one-boat Western system, as developed on the 
Pacific Coast of U.S.A. and Canada. The other basic systems are described. The fish can be carried either by the purse seme vessel or by 
carry-away vessels. This has a major influence on design. 

Selection of the size of the purse seiner is described, together with the general requirements for an efficient purse seine system mad 
me important baste design considerations. The most important design consideration is the selection of the fishing method. After the method 
has been selected, arrangement of work space can be made and proper equipment selected. In most cases, the combination fishing principle 
shall be taken into account in the design. 

The arrangements of fishing vessels, methods of fishing, and mechanization of the fishing process are discussed for the world's most 
important purse seine fisheries, together with suggested changes. 

LA PECHE A LA SENNE TOURNANTE 

On capture plus de poissons par la peche au filet coulissant, qui est la plus importante m&hode de peche au filet touraant, que 
par n'importe quelie autre methode, et le plan des bateaux pour la peche a la senne s'est amelk>r6 rapidement pendant tea dernieres annfet. 
Les systcmes tea plus importants de peche a la senne sont le systeme a deux bateaux, qui est employ* par les pecheurs de harengs norvemnt 
et par ceux de la cdte orientate des Etats-Unis pour la peche au menhaden, et le systeme occidental a un bateau employ* sur la cote Pmonque 
des Etats-Unii et du Canada. Une description est donnee des autres systemes de base. Le potsson peut 6tre transport* soit par le bateau de 
peche a la senne, soit par des bateaux de transport. Ceci a une grande influence sur le plan du bateau. 

On indique le choix de la grandeur du bateau pour la peche a la senne tournante ainsi que les exigences requites pour un systeme 
emcace de peche et tos considerations primordiales pour le plan du bateau. La methode de peche est le point le plus important & considerer 
pour le plan du bateau. Une fois la methode choisic, il convtent de determiner Tespace et requipement necessaires pour le travail Dans la 
plupart des cas, le plan du bateau devra prevoir une peche mixte. 

L*amenagement des bateaux, les mcthodes et la mecanisation des prooedes de peche, sont dtscutes pour les plus tmportantes 
pecheries a la senne tournante du monde, ainsi que les modifications proposees. 

LA PESCA CON REDES DE CERCO 

La pesca con redes de ccrco, que es la mas productiva de todas, y las formas de los barcos que emptean esas redes ban mejorado 
rapidamente en los ultimo* afios. Los sistemas mas important** de pesca con redes de ccrco son el de 2 cmbarcacioaes empteado en la 
pesca del arenque en Norucga y en la de alacha en la costa oriental de los E.U.A., y el de 1 embarcacion, practicado en la costa del Pacffico 
del Canada y los E.U.A. Se dcscribcn ambos sistemas. El pescado lo transporta el barco de pesca al ccrco o barcos de transports Esto 
influye mucho en las formas. 

Se explican la selecci6n de las dimensions del barco de pesca con redes de ccrco, las condicioncs generates que se han de reuntr 
para lograr un bucn sistema de pesca con redes de ccrco y consideraciones de importancia relacionadas con el proyecto, cntre Las cutlet hi 
mas importante es la eleccibn dc los metodos de pesca. A continuacidn se hace la destribucidn de tos espacios donde se realizarin las facnas 
y se selecciona el equipo. En algunos casos, al preparar el proyecto se han de tener en cuenta las posibilidades de emplear diversos metodos 
de pesca. 

Sc estudian: distribuci6n a bordo de los pesqueros, metodos dc pesca y mecanizacidn de la pesca en algunas de las pesquerias con 
redes de ccrco mas importantes del mundo. Se proponcn algunos cambios. 



MORE fish arc caught by encircling nets than by 
any other basic type of fishing gear. By far the 
most important type of encircling net is the purse 
seine. 

Definition: A purse seine is a form of an encircling net 
having a Une at the bottom passing through rings 
attached to the net, which can be drawn or "pursed". 
In general, the net is set from a boat or pair of boats 
around the school of fish. The bottom of the net is 
pulled dosed with the purse Une. The net is then pulled 
aboard the fishing boat, or boats, until the fish 
aw concentrated in the bunt or "fish bag". The 
fith art then removed from the fish bag aboard 
the fishing vessel or an accompanying fish-carrying 
vessel. 



In U.S.A., purse seining accounts for over SO per cent 
of all fish production. Throughout the world, most of the 
herring-like fish are caught by this method. The world's 
great reduction fisheries are an based on purse seining. 
The fish reduction industry is growing particularly in 
many of the relatively undeveloped fishing areas of the 
world, and along with this purse seining is growing in 
importance. 

In many areas, the more efficient purse seines are 
replacing other traditional gear. The efficiency of purse 
seining has increased recently, with the introduction of 
synthetic nets, mechanization, electronic fish detection 
and improved vessel design. In the last few yean, purse 
seining has been found to be extremely effective for 
catching codfish in the Lofoten Islands off Norway, and 



FISHING UOATS OF THE WORLD : 2 TACTICS 



otter applications are being found for sunken pone 

There are many variations of the general procedure 
described above. This paper will describe the design and 



equipment of modem purse seine vessels, the methods 
u*ed in many of the important purse seine fisheries of the 
world and also the traditional types of boats. The reasons 
behind evolution of the traditional designs are set forth, 
together with suggested changes in method and design. 
No attempt has been made to cover all of the types and 
methods of encircle-net fishing, and the subject has been 
limited to the more important fisheries. 

Purse seining has evolved during the last 60 or 70 years 
--primarily through the efforts of fishermen, with little 
attention being paid by naval architects, factory owners, 
or fisheries technologists. During the last 20 years rapid 
development has been made in purse seine vessel design 
and methods on the West Coast of U.S.A. and Canada. 
In the last 5 years this development has increased in 
tempo, with the introduction of mechanization of the 
net-handling process. 

In general, purse seining is little known and understood 
in northern Europe, except in Norway and Iceland. Even 
there few of the new methods and vessel designs have been 
tried As was very evident at the FAO Fishing Gear 
Congress of 1957, much more work has been done in the 
development of modern trawling than in the improve- 
ment of purse seine methods and vessels. The deep sea 
trawler had captivated the interest of naval architects 
and engineers far more than the generally smaller, and less 
complicated, purse seiner. Very few naval architects 
have employed themselves in the betterment of the purse 
seiner outside North America, and in most cases the 
vessels have been built along the traditional lines of other 
types of vessels common to the fishing area, with the 
fishing method adapted to these vessels. 

With the increase in mechanization in many parts of 
the world, it is necessary to improve all phases of the 
purse seine operation so as to increase the productivity 
of man and equipment in order to remain competitive. 
It is possible in most cases to design vessels and equip- 
ment and select methods which can increase efficiency 
well over 100 per cent. 

The major purse seine fisheries of the world can be 
grouped as follows: 

Norwegian and Icelandic herring fishery 

U.S. East Coast and Gulf menhaden fishery , 

U.S. Pacific Coast, Alaska, and Canadian salmon, 
herring, sardine, mackerel and tuna fishery 

Japanese and Korean sardine, mackerel and skip- 
jack fishery 

U.S.S.R. herring fishery 

West Coast of South America anchovy and tuna 
fishery 

South and South West Africa pilchard and mackerel 
fishery 

Portuguese, Spanish, French, and North West Africa 
sardine fishery 

+ Angola pilchard and mackerel fishery 



BASIC PURSE SEINING SYSTEMS 
Two-boat fysttn 

This is the oldest system of purse seining, and was first 
developed on the East Coast of U.S.A. in the menhaden 
fishery. It was introduced into the Icelandic and Nor- 
wegian herring fisheries in the early 1900s (Kristjonsson, 
1959). In this system, two small seine boats 32 to 36 ft. 
(9.75 to 1 1 m.) in length are carried in davits on board a 
larger vessel, which is called a "steamer*' (fig, 3). On 




Fig. J. Two-boat purse seining system 

reaching the fishing grounds the small boats are launched, 
each carrying half of the purse seine net. The boats run 
breasted together until the school of fish is located, and 
the set begins. The boats, on setting, go in opposite 
directions, encircling the school of fish and coining 
together 180 degrees from where they started setting the 
net. The net is pursed, using a purse winch in one or both 
of the boats, and the net is then putted from each end by 
the crew or power block in the two boats until the fish 
are sufficiently raised and concentrated for brailing or 
pumping. The "steamer" then comes alongside and 
removes the fish from the bunt of the net with either a 
large brail or a fish pump. 



[32] 



FISHING METHODS AND DECK ARRANGEMENT - PURSE SEINING 



The two-boat systen of purse leaning evolved in the 
day* before the modern gaiolme and diescl engine, when 
it was necessary to row arouad the flsh. The fish- 
catohing boats were carried ant to the fishing grounds on 
the larger vessel, which was either sail or steam powered, 
and were small enough to be propelled around the fish by 
oars. There has been little change in this general method 
since engines were put in the seine boats. 

The two-boat system has the following disadvantages: 

It uses a large number of fishermen. The individual 
productivity of each fisherman is relatively low. It 
does not tend itself to mechanization 

Launching and hoisting the smaller boats in rough 
weather is hazardous, and much fishing time is lost 
due to the problem of handling the small boats 

The "steamer" must be large enough to carry the 
small seine boats, which eliminates this system for 
many species of fish where a large cargo capacity 
vessel is not required 

The length and depth of net are limited because of 
limited space in the small seine boats 

The work is extremely back-breaking and hazardous 
because of the necessarily small and unseaworthy 
boats which do not provide a good working platform 

Investment per net is very high. Instead of having 
several nets working per carry-away unit, only one is 
used 

The advantages of the system are: 

Larger carrying vessels can be used, which travel at 
high speed, complete with their fishing units 

The small seine boats particularly in Iceland and 
Norway compete for the schools of fish, and the 
large single vessels setting the nets would find it 
difficult to manoeuvre in such crowded conditions 

With the two small seine boats, it is possible to 
encircle quickly the school of fish 

The net can be hauled rapidly because it is pulled 
from both ends simultaneously 

Western one-boat system 

The Western one-boat system shown in fig. 4 is becoming 
increasingly popular and is being adopted in many areas 
where fishing is developing. The net is carried aboard 
the catcher vessel, and in most cases this vessel also carries 
the catch back to the factory. A small auxiliary boat is 
used, called a "skiff". To surround a school of fish, the 
large vessel releases the "skiff", which is attached to the end 
of the net. The skiff tows away from the seiner as the 
seiner is describing a circle around the fish. The seiner 
joins together with the skiff and purses the net. The net is 
then pulled aboard the seiner until the fish are sufficiently 
concentrated to brail into the fish hold of the seiner, or in 
some cases into a carry-away vessel, which may be 
working in conjunction with the seiner. The Western 
purse seiners are arranged with the machinery and deck- 
house forward, so as to give the maximum working area 
in the stern of the vessel for handling the net This 
system lends itself most favourably to mechanization and 
high manpower efficiency. 



Advantages of the one-boat system are: 

9 Adaptability to the mechanioUkai of the net haaSng 
process by use of a powered fatock aod highly 
mechanized handling of rope or wire purse line 

Utilizes a minimum of manpower 

Adaptability to systems capable of fishing in rough 
weather 

Safety to fishermen and no back-breaking labour 

Ability to carry and handle large nets efficiently 

Flexibility of operation carries own fish in periods 
when fish are scarce and works with other vessels to 
carry away fish during periods when fish are 
abundant 

Disadvantages are: 

Clumsiness of extremely large vends, which would 
make them unsuitable for purse seining certain types 
of fish such as menhaden 

The net is hauled from only one end, which, theo- 
retically, is not as fast as hauling from both ends. 
This disadvantage is not so great because of the 
rapidity of hauling using a powered block. 

Portuguese system 

The Portuguese system, which is used to some degree in 
France, Spain, and the Northwest coast of Africa, is 
referred to by many in those countries as the "American 
system'*. Evidently this system was derived from the 
American West Coast system of carrying the entire net 
aboard the purse seiner, setting it out with a skiff attached 
to the end. 

The bunt, or "fish bag'* of the net is in the end, in 
contrast to the lampara style, with the fish bag in the 
middle, as used in the Mediterranean. The only basic 
difference in the Portuguese system from the Western 
system is that a large amount of manpower is used to haul 
the nets. On the West Coast of U.S.A., the nets have been 
historically pulled over power rolls, and strapped with 
the boom (lifting the net in successive bites, with a single 
fall from the boom) now a powered block is generally 
used. 

With the Portuguese system, it is not possible to stack 
the net on the stern of the boat because from 20 to 30 men 
are lined up along the rail pulling web. From 3 to 5 men 
coil the cork line on the stern. Several men are used for 
pulling corks in the bow, and several more for pursing 
(fig. 32). The body of the net is stacked for about 30ft. 
(9 m.) along the side of the vessel. The Portuguese 
method of setting the net and pursing is generally similar 
to the Western system. 

The arrangement on the Portuguese boats with the 
deckhouse and machinery amidships does not lend itself 
readily to convenient handling of the net without modi- 
fication of the system (fig, 32)* 

The main disadvantage of the system is that it needs 
a large amount of manpower. Otherwise it is, in general, 
similar to the Western system. 



South African 

In South Africa the net and fish are aft carried on one 

seine boat; however, a modified lampara-styie apt with 



{33] 



FISHING BOATS OF THE WORLD : 2 ~ tACtlCS 




A. Storting setting of net 





C. Picking up foreword purseline from skiff 




E. Pursing 




6. Pulling web 



8. Setting completed 




D. Towing 




F Lifting rings 




Fig. 4. One-boat purse seining system 
[34] 



FISHING METHODS AND DECK ARRANGEMENT PURSE SEINING 



purae line it used. This system was well described by 
du Ptessis (1959), The South African boats at* very 
similar in arrangement to European "drifters", and the 
system does not lend itself well to mechanization; 
however, it is relatively efficient for the small nets used. 



Drums were first introduced in 19S1 in British 
Columbia and the Puget Sound areas of the Pacific West 
Coast They have been primarily successful in handling 
relatively shallow salmon seines, and are the fastest, most 
efficient method yet devised (Smith, 1954; Schmidt, 1953). 
Unfortunately, there are various problems to be sur- 
mounted in using a drum seine, of which gear damage and 
special methods of handling the net appear to be the most 
serious. The drum seine lacks flexibility in adapting to 
the traditional nets that are in use. Prior to the introduc- 
tion of the powered block, about 30 boats were converted 
to drum seining, and several new vessels were built. In 
drum seining, the seine is wound on a large drum mounted 
on the stern of the vessel. A spooling device, consisting of 
two vertical rollers moving in a track on the stern of the 
vessel, is used to spool the net back and forth while it is 
being wound onto the drum. The entire net from cork 
line to lead line is bunched together as it goes through the 
spooler and winds onto the drum. The drums have been 
mostly hydraulically powered; however, some of them 
are run mechanically through shafting and gearing. The 
spoolers have been primarily hydraulically actuated. 
Some of the drums have been mounted on a rotating 
carriage in a tub, with spooler mounted on a frame 
attached to the drum, such that the entire mechanism 
can be rotated through 180 degrees. This allows picking 
up the net on the side, similar to the position of pulling 
the net onto a seine table. The fishing vessel must have a 
wide, square stern, which in most cases is recessed with a 
tub, so as to lower the centre of gravity of the drum. 
The net is set out over the stern of the vessel, allowing the 
drum to rotate against a brake. 

Since the introduction of the powered block during the 
last three years, only about 6 drum seine vessels have been 
built or converted. It would appear that the simplicity, 
low initial cost, and flexibility of the powered block are 
advantages over the drum. The drum seine method must 
not be discounted, however, as it can be successfully 
applied to various types of fishing, and may eventually 
gain more favour after additional development 

U.S. mftdterd and Icelandic herring one-auxiliary boat 



This system is a transition from the two-boat system used 
in the menhaden and Icelandic herring to a modified one- 
boat system in which the net is carried in one auxiliary 
seine boat that is towed by the larger vessel. Obviously, 
the only justification for this method is that the large boat 
does not have appropriate space on the stern or alongside 
the house from which to handle the net. The large boat 
tow the net-handling boat atengwde the quarter, to make 
the tet around the school of fish* In effect the small boat 



is a floating seine table. Hie large boat thea purses the 
net and the net is hauled bade into the smafl seine boat, 
TTiis system is makeshift at best, and should be coosktared 
only as a transition to utilize existing equipment where 
the fishery cannot justify the construction of proper 
Western-style purse seine vessels. 

METHOD OF CARRYING FISH 

One-boat carrying its own fish 

In the Norwegian herring and menhaden two-boat system 
the steamer not only carries the two fishing boats to the 
grounds, but is used to transport the fish back to the 
factory. Each "steamer" is therefore a complete fishing 
unit working independently. When the steamer is loaded, 
it is necessary for it to leave the grounds, with its net, to 
unload. 

In the Western system, the purse seine vessel usually 
carries its net and fish. On the U.S. West Coast most of 
the salmon, sardine, and tuna seiners operate in this 
manner. The salmon seiners, however, are unloaded into 
tenders (carry-away vessels) each night to transport the 
fish to the canneries. The California sardine seiners carry 
their own fish, however, when big sets are obtained 
many boats of the fleet may load up from one net. 
The tuna purse seine vessels operating out of Southern 
California and South America all carry their own fish. 
In South Africa, Angola, Portugal, Spain, France, and 
Northwest Africa, most of the purse seiners carry their 
own catch. 

One boat working with carry-away vessel 

The best example of this is the Canadian winter herring 
fishing, where, although the seine boat is a complete 
fishing unit capable of carrying fish, in most cases these 
boats work in conjunction with tenders which carry the 
fish the long distances back to the reduction factory. It is 
generally only when dose to the factory or when all of 
the carry-away vessels are loaded that the seine boat will 
load itself and return to the factory. Obviously the 
advantage of this system is that it allows the fishing unit 
to stay on the grounds, keeping its net and crew more 
productive while the carry-away vessels run back and 
forth to the factory. The consideration of whether the 
fishing boat should carry its own fish or work in con- 
junction with carry-away vessels is of prime importance 
in the selection of the design and arrangement of the 
fishing vessel. 

SIZE OF BOAT 

Some of the factors influencing the size of the purse seiner 
are: 

Governmental regulations 

Distance to fishing grounds 

Maximum daily catch 

Average daily catch 

Stability and adequacy of working platform, 

together with size and weight of net 

Availability of carry-away boats 

Use of vessel for other methods of fishing 



135J 



PISHING BOATS OF tHB WORLD: 2 -~ TACTICS 



The influence of these factors will be illustrated by the 
foUowing specific examples: 

(1) GomMMOta! rrgriarion; In Alaska, protective laws, 
which are based partially on conservation and partially 
on protecting die local fishermen, have been passed which 
limit the lengths of fishing boats. For instance, in South- 
eastern Alaska, the Alaska limit has been in effect for 
some time, which prohibits the operation of any fishing 
vessel of over SO ft. (15.3 m*) registered length. From this 
has developed what is known as the Alaska limit com- 
bination purse seiner. In other areas in the fishing world, 
there are regulations which tend to restrict the size and 
type of vessel. In general, this type of restriction is non- 
progressive and detrimental to the development of 
efficient fisheries. 

(2) Distance to fishing grounds: This criterion has had 
a major effect on the design of the tuna seiners, inasmuch 
as they must travel many days, and sometimes as much as 
three weeks, to the fishing grounds. To make this type of 
operation profitable, a large fish-carrying capacity is 
necessary. Tuna seiners are getting larger and larger, 
and at the present time are up to 150 ft. (45.7 m.) in 
length and capable of carrying up to 400 tons of frozen 
tuna. 

In many areas, such as the anchovy fishing grounds of 
Peru and northern Chile, and the fishing grounds of 
South and South West Africa, the fishing vessels rarely 
go more than 1 or 20 miles from the factory. In this case, 
the size of the vessel can be determined primarily by the 
expected maximum daily catch. At present, in the newer 
areas, the vessels make two and three trips a day. The 
trend is to increase the size of the vessel not because of 
distance, but because of the expected daily catch. 

(3) Daily catch: The size of the maximum daily catch 
and the average daily catch are probably the most im- 
portant factors influencing size. For instance, most of 
the menhaden vessels have reached the size (approxi- 
mately 130 ft. or 40 m.) at which they can handle what 
would be considered a large day's fishing. These vessels 
range outward to approximately 100 miles from the 
factory, generally returning each night with their catch. 
Recently some vessels of up to 200 ft. (60 m.) in length 
have been built, and have been refrigerated so that they 
can stay at sea for up to one week before unloading. It 
has not as yet been determined whether this is a profitable 
size of vessel. The South African boats were originally 
50 ft. (15.3 m.) in length and carried 80 to 100 tons of 
fish. Each year they are increasing the length of these 
boats to a point where they can carry as much as 200 tons 
of fish. The fishing grounds in South and South West 
Africa are close to die factories, and it has been common 
for these boats to make several full-load trips a day. 
They are now finding that, with improved nets and the 
echo sounder, bigger and bigger catches are being made ; 
consequently the size of the vessels is increasing. The next 
step would be the introduction of carry-away boats that 
would pump the fish out of the nets, carrying them back 
to the factory, allowing the catcher boats to stay on the 
ground. 



(4) Working platform: As mechanization is increasing, 
the desirability of having a stable vessel with a dear deck 
area at the stern is becoming more important, A poor 
working platform is afforded in the small two-seine boats 
as used in Norway and the U.S. menhaden fisheries. A 
good working platform is afforded by the large herring, 
sardine, and tuna seiners on the U.S. West Coast. 
Complete mechanization is possible aboard these vessels, 
with the crew exerting practically no physical effort. 

(5) Availability of carry-away boats: If a system using 
carry-away boats to take the fish back to the factory is 
used, the size of the purse seiner can be relatively small. 
It is the author's opinion that vessels from about 45 to 
55 ft. (13.7 to 16.8 m.) can efficiently handle the largest 
nets, provided they work directly with carry-away 
vessels that are equipped with pumps. It would be 
possible with, say, a 50 ft. (15.3 m.) seiner, similar to 
fig. 27 to handle the largest pilchard, sardine, anchovy, 
menhaden, and herring nets with not more than six men. 
These boats can be so mechanized that it would be 
unnecessary for helper boats, customary in Norway, to 
be used in drying up the net. 

REQUIREMENT FOR AN EFFICIENT 
PURSE SEINING SYSTEM 

The design of a purse seiner should meet the following 
general requirements: 

(1) Rough weather: The vessel must be designed to fish 
in rough, as well as in calm weather. Many of the purse 
seine vessels and systems being used are ineffective a large 
part of the time as they cannot be used in high wind and 
rough seas. It is the author's opinion that a vessel and 
system can be devised that will fish in much rougher 
weather than is at present being done in most areas. 

(2) Manpower efficiency: The system should handle 
large nets with a minimum amount of manpower in 
most cases the modern systems of mechanically handling 
not only use fewer men, but are more productive, in that 
more sets can be made during an equivalent fishing period, 
and the net and fish can be handled faster. 

(3) Safely of fishermen and elimination of hard, back- 
breaking labour: As education and the standard of living 
of the various fishing areas increase, it becomes more and 
more necessary to improve safety standards and to 
eliminate unnecessary hard, back-breaking labour, so as 
to attract better fishermen to the industry. 

(4) Speed ef setting and hauling: It is important that the 
net should be able to be set out fast, and in many cases 
the circle made in either direction, to left or right. 
Likewise, the problem of attack from sharks, which 
occurs in many areas, is lessened with the speed of 
hauling. 

(5) Brafltaf speed: Efficient brailing systems should be 
devised to remove the fish from the fish bag as rapidly as 
possible. Often the hauling speed is very good, but 
brailing occupies too much time. The fish pump (Burgoon, 
1959; Rotas, 1959) is being increasingly used. It is at 
present universally used in the U.S. menhaden fishery, and 
is being introduced in South America, Whereas rapid 



[36] 



FISHING METHODS AND DECK ARRANGEMENT FURSE SEINING 

than resistance, whic* are of primary m^ It ha* 

been found, however, that low resistance vessels can be 
designed within the more important limitations that go 
with the fish-catching method. 

After the general system is decided, arrangement of 
working space can be made, and proper equipment can 
be selected for net hauling, pursing, and fish handling. 
Stability is of prime importance if mechanical systems of 
hauling are to be accomplished. Draft is often a con- 
siderationparticularly in such areas as the U.S. East 
Coast menhaden fishery, some areas of the Alaska salmon 
fishery, and some of the anchovy fisheries of South 
America. The following outline is suggested in evaluating 
a design: 

Selection of method of handling net 

Arrangement of working space to best suit this 
method 

Selection of best possible hull to go with the above, 
providing adequate stability and low resistance, and 
meeting draft limitations 

Proper location of fish hold space so that vessel will 
not trim either by bow or stern when being loaded 

Selection and arrangement of proper equipment; 

(a) Net hauling equipment 

(b) Pursing and purse line-handling equipment 

(c) Fish handling (brailing or pumping) 

Unloading considerations arrangement of vessel 
so it can be easily and rapidly unloaded 

Adequate accommodations to attract high quality 
fishermen. 

COMBINATION FISHING 

So far, in this discussion, consideration has only been 
given to purse seining and the purse seine method of 
fishing. It is becoming more and more apparent that in 
most fishing areas vessels should be able to accomplish 
efficiently at least one other type of fishing in the "off 
season", so as to obtain maximum utilization of the 




Fig. 5. Pumping menhaden with JO in. (305 mm.) centrifugal pump 

brailing is accomplished in Norway, Canada, and Cali- 
fornia, the fish pump has advantages in requiring fewer 
men, less time lost in starting the operation, and allows 
continuous operation (fig. 5). 

(6) Efficient pursing: Again, setting, hauling, and brail- 
ing can be speeded up, but to little avail if the pursing 
system is too slow and requires too much manpower. 
Modern, drum-type winches, using wire cable, are the 
ultimate answer (fig. 6). 

(7) Night fishing: The purse seine system should be 
equally efficient at night as it is during the day. In 
general, the Western system can be accomplished safely 
at night. The system using two small seine boats, such as 
the menhaden and Norwegian herring systems, does not 
lend itself safely to night fishing. 

BASIC DESIGN CONSIDERATIONS 

The most important design consideration is selection of 
the purse seine method. This means selection of the type 
of net and system of hauling, method of pumping or 
brailing, and unloading, The next most important con- 
sideration is whether the boat is to carry its own fish or 
whether the fish will be carried in auxiliary vessels. From 
the above considerations it is possible to block out a 
general scheme. The design of the hull below the water is 
less important than the working arrangement and 
fishabtiity. Of course, good naval architectural practice 
should be used. There are many considerations, other 




[37] 



FISHING BOATS Of THE WORLD : 2 TACTICS 





Atlantic cooft Mtnhodtn purssboats 



Pocific coost MiMboat 



Pacific coast ssins skiff 





/South africop pilchard boat 



Portugtse 
ins boat 




Fig. 7. Application of] 




/ Norwsgian hsrnng pursaboots 



tyr*t of pur M Ml** 



Pursing is acnftmpfahod usually by pulling the maoila, 
hemp, iteel wire or nylon purte fine at both ends with 
the me of a purse wine*, with several turns being taken 
around each one of two winch heads. 

In the 1930*8 a Tacoma shipyard developed a type of 
wire purse winch for use on the large herring, sardine,. 



WMfl purttaf it >*' Kit 
toward purwUr* it eonwctod 
to ttw ft perttftm art porttd 
on Kw main 



Tow Hnt drum 




FISHING METHODS AND DECK ARRANGEMENT PURSE SEINING 

vessel throughout die year. Hanson (1955) discusses the 
combination principle in detail In Europe most vessels 
being used for purse seining have evolved from other 
traditional types* There is a marked resemblance 
between trawlers, drifters and purse seiners in these 
areas* In most of the areas, as in Iceland, more con- 
sideration has been given to the proper handling of drift- 
nets, long lines, and trawls than to the development of an 
efficient purse seining system. On the U.S. West Coast 
and Canada, the vessels have been developed primarily as 
purse seiners, and have been modified for use as trawlers 
and long liners. Where the purse seine fishery is the most 
valuable in terms of monetary return, it is only logical 
that this approach be used. It is surprising, however, how 
well the West Coast purse seiner lends itself to stern 
trawling and long lining. It is the author's opinion that 
purse seine vessels similar to fig. 20, 21, 24, 27, 28, 29 and 
30 not only convert well to trawling, but make superior 
small stern trawlers with many advantages over the con- 
ventional side trawler type. Vessels of this design are also 
engaged in the North Pacific halibut fishery, and the 
largest landings in the last few years have been primarily 
by these vessels, rather than by the traditional schooner 
type, which is similar in design to the European long- 
liners and drifters. In the conversion of the U.S. West 
Coast purse seiner to trawling, maximum use is made of 
the boom in handling the trawl net, as described by 
Alverson (1959). 

EQUIPMENT FOR PURSE SEINING 
Powered block 

The Puretic Power Block (Schmidt, 1959) and system of 
hauling nets has in recent years probably done more than 
any other one thing to revolutionize the purse seine 
fishery. The powered block is in use by over 1,000 boats 
on the Pacific East Coast from Alaska to South America. 
It is gradually being introduced in Norway, Iceland, 
Korea, and other areas. The U.S. East Coast menhaden 
fishery is now about 80 per cent, converted to the powered 
block, even in the small seine boats. In this conversion, 
twelve men have been eliminated from each net, thereby 
doubling the labour efficiency. In addition, faster hauls 
are being made on larger schools offish. As stated by the 
author (1959) 'The power block is a new concept in net 
hauling whereby fish nets can be hauled from the sea 
faster, with fewer men and less toil, with less nit wear 
than by traditional hand methods'*. It is not a matter of 
whether a traditional system can be adapted to the 
powered block, tat whether a system can be developed 
using the powered block which will increase the produc- 
tivity of the fishery. In all areas where the powered block 
has been effectively tried, either a traditional system has 
been modified or a new system has been successfully 
developed Fig. 7 shows applications of the powered 
Mode to various traditional boat types and basic 
methods. la most cases, tome redesign or rearrangement 
of the vesad would eventually follow the introduction of 
the powered btock. 



Fig. 8. Pursing with wire purse line on special type 3-drum winch 

and tuna seiners on the U.S. West Coast (fig. 8, 9). This 
type of winch was a decided advancement for the large 
boats, and allowed them to use wire cable in pursing. 
Other U.S. Western boats ran the wire from hardened 
winch heads on the conventional winch to drums, where 



Tow Mw drum 




Fig. 9. Pursing with wire on standard winch, showing hods to r**is 



the wife was wound (fig. 10). Before setting out, all the 
wire is wound on one drum. In many of the purse seining 
areas where mechanization is developing, the change to 
wire purse line is proceeding rapidly. 

Fig. 6 shows a new type of hydraulic purse winch for 
the large tuna bait boats that are converting to parse 



[39] 



FISHING BOATS OF f 8 WGIUUD< : 2 ~* TACTICS 




fig. 10, Pursing with wire on standard winch, showing leads to reels 

seiners. This all-hydraulic winch has three drums and 
three gypsies each with separate controls and hydraulic 
motor for independent operation. The capacity of the 
winch is 5 tons, and it is capable of handling a purse line 
of & in. (14.3 mm.) diameter, 800 fin. (1500 m.) long. 
Sets of up to 300 tons of skipjack have been made with 
this winch in conjunction with a powered block and 
nylon tuna seine in Peruvian waters. 



Brailmg using the conventional brailer is well developed 
in Norway, Iceland, and Canada. The use of pumps is 
increasing, and will probably supersede brailing in the 
next few years particularly where the fish is to be used 
for reduction. For tuna and salmon the conventional 
brailing methods will undoubtedly continue. In salmon 
fishing, when small catches are being made, the fish are 
rolled aboard with the use of the powered block, by 
bringing the end of the bunt of the net across to the hatch. 
This has speeded up the process considerably. Special 
"brailer blocks'*, or releases, are used in Norway and 
Canada. In Norway it is the Haahjem brailer block, and in 
Canada the Wilfro block. This device holds the bottom of 
the brailer closed until it is tripped by pulling on thtf wire. 

Miscellaneous equipment 

Much hydraulic equipment is being installed on U.S. 
Western purse seiners and used in conjunction with the 
hydraulic powered block circuit. Lightweight, compact, 
high pressure hydraulic mast- and boom-mounted 
winches have been developed for raising and swinging the 
boom, and for brailmg. Hydraulic anchor winches have 
also been developed which operate off the powered block 
circuit R is very important to have a conveniently 
operating anchor winch, as it is often necessary to anchor 



particularly when operating In the turf, fa South 
America, most of the seine vewels do not yet have anchor 
winches, but it would be an extreme advantage when 
fishing anchovies dose to the breaker line. Considerable 
hardware has been developed for handling purse seines 
such as a special skiff release, purac line release, and snap 
purse rings. Two types of snap purse rings are used the 
Norwegian-Iceland type which the author introduced to 
the U.S.A. in 1956, and a new type developed in Cali- 
fornia by Peter Maiorana. The snap purse ring has 
several advantages particularly when used in conjunc- 
tion with the powered block method. 

ANALYSIS OF VESSEL TYPES AND METHODS 

AS APPLIED TO IMPORTANT 

PURSE SEINE FISHERIES 

The following is an analysis of the type and arrangement 
of fishing vessels, and specific methods, with suggested 
changes for the more important purse seine fisheries. 

UNITED STATES EAST AND GULF COASTS 

The U.S. menhaden fishery extends from New England to 
northern Florida, and from Florida to Texas in the Gulf 
of Mexico. This is one of the two largest reduction 
fisheries in the world, and annual production has reached 
over one million tons of fish. The fishing season lasts 
nearly six months, and the fish are concentrated in large 
schools. Most of the fishing vessels are owned by the 
factories. Robas (1959) describes the general method and 
type ot vessel. The basic system is the two-boat system. 
The menhaden steamer is from 100 to 200 ft. (30 to 60 m.) 
long, of relatively shallow draft, and is capable of carrying 
from 150 to 600 tons of fish. These vessels are highly 
powered, with speed of up to 15 knots. A number of 
138 ft. (42 m.) wooden minesweepers have been con- 
verted, and are successfully being used by the industry. 
Many of these vessels are twin screw, with up to 1 ,200 h.p. 
Recently some of the larger vessels have been refrigerated, 
using a chilled sea-water circulating system. 




rig. //. Modern 



[40] 



FISHING METHODS AND DECK ARRANGEMENT - PURSE SEINING 

te f aU^ 




Fig. 12. Modern aluminium menhaden boats ready to make set, 
36 x 8ft. 9 in. (Ji x 2.7 m.), 100 h.p. gasoline engine and power block 

Arrangement: The menhaden steamer (fig. 11) has the 
engine or engines in the stern, the fish hold amidships, 
and pilot-house and crew's quarters forward. These 
vessels take on the general aspect of a tanker. All 
menhaden steamers are equipped with fish pumps, 
10 in. (305 mm.) dia. being the most common size. The 
fish pump is 'located in the after part of the forward 
deckhouse, and is driven by a diesel engine of from 100 
to 200 h.p. (fig. 5). The small seine boats, which are 
called "purse boats" are carried in davits alongside the 
machinery house aft. A hydraulic system is used for 
hoisting the boats. 

Small seine boats: The "purse boats" are as shown in 
fig. 12. In 1958 aluminium purse boats were introduced 
to the industry, made from J and &in. (6.35 and 4.8 mm.) 




fleet has now converted to aluminium purse boats. 
They are 36 ft. long by 8 ft 9 in. wide (11 by 2.7 ntX aod 
were developed to provide a more tobte worki 



fonn and more working space for use with the powered 
block, without increasing the weight. The steel boats 
which have been replaced wejs 32 ft (9,75 m.) long, and 
it has been found that the larger, lighter aluminium boats, 
even when used with the powered block, are considerably 
more stable, buoyant, and seaworthy. The fishermen 
report that these boats are much drier, and they can be 
bunched, and fished, in rougher Weather With tht 
powered block than was possible with the smaller sted 
boats, fishing by hand. It can be seen from fig. 13 that 




Fig. 13. Hauling menhaden seine with hydraulic power block supported 
by aluminium block crane (note the easy work of the fisher men) 



Fig. 14. Modern method of strapping menhaden net with 3-ton 
hydraulic winch to dry up the fish for pumping (the largest sets can be 
handled with ease in this manner) 



hauling the net in the overhead position does not cause 
excessive angle of heel. Actually, the resultant heeling 
force is about the same as when pulling the net by hand 
over the gunwh^le, the only difference being that the 
powered block exercises greater force than is possible by 
hand. 

Method of fishing: The method of fishing has been 
somewhat modified by the use of the powered block, 
strapping winch, and fish pump. Aeroplanes art uni- 
versally used in the menhaden industry for spotting fish. 
Approximately one aeroplane is used for each five boats* 
Not only does the aeroplane locate the schools of fish. 



[41] 



FISHING BOATS OF THE WORLD r2 TACTICS 




Fig. 15. Old method of dry fog MB menhaden for pumping (this crew 
has been reduced by half by the strapping method) 

but actually sets the purse boats around the school by the 
use of radio. Six men are now used in each purse boat 
with the powered block and strapping system whereas 
formerly twelve men were needed. By studying fig. 13 
and 14 it will be seen that the men do very little physical 
work. One of the largest operators in the industry has 
applied electrical attraction, in conjunction with a fish 
pump, to speed up broiling. This allows pumping before 
the fish would normally have been sufficiently concen- 
trated, and together with the strapping system has 
speeded up this part of the operation, 

Mechanization: In 1958 and 1959 nearly 80 per cent of 
the menhaden industry converted to the use of the 



powered Mock in the purse boats. The powered block is 
supported by a specially developed hydraulic crane 
(fig. 13; Schmidt, 1999). HydrauHc reel* for spooling the 
pane toe have also been introduced into the new pone 
boats. In 1958 the system of strapping the net to dry up 
and concentrate the fish for pumping was finally adopted . 
Fig. 14 shows the strapping operation in which the 
net is lifted by hydraulic winch, using two single 
falls to the gaff on the mast of the steamer. A two-drum, 
3-ton, high pressure hydraulic winch was developed for 
this purpose. Each drum is on an independent hydraulic 
circuit, using hydraulic power for both raising and 
lowering to ensure positive control. The power block cut 
down the manpower required while pulling in the net 
much more rapidly, and the strapping system made it 
possible for this small crew to dry up the net without 
additional help. This system works with a minimum of 
manpower, even on the largest schools of fish. It also 
allows fishing in considerably rougher weather than was 
possible before. 

Suggested change* : It is the author's opinion that the 
menhaden system has developed about as far as the basic 
system will allow, with the use of these modern aids: 
aeroplanes for spotting, powered blocks, strapping 
winches, electrical attraction, the fish pump, and greatly 
improved aluminium purse boats. A minor improve- 
ment is suggested in fig. 16, which shows an improved 
purse boat as designed by the author. This design is a 
further refinement to allow more convenient operation 
with the powered block, and to give the boat captain 
better visibility and control of the boat. 

Any major increase in efficiency must come from a 
change in basic method. At present experiments are being 
made using one-boat systems in the menhaden fishery. 




Q Of I t* t 

Fig. 16. Improved design for menhaden pi 
[42] 



Fwtbcr cisperiiiWBtatiOT of this type should be conducted 
to determine whether tome form of OQ**oat system 
would not be superior to the pretest two-boat system. 
A design similar to fig. 22 would be capable of handling 
the menhaden bet with only six, rather than twelve, men 
needed in the purse boats. A boat of this type with 
powered block working with a carry-away vessel and 
employing the strapping system for drying up would be 
able to handle large schools of fish rapidly with increase 
in manpower efficiency and ability to fish in rough water. 



NORWAY 
Henrteg 

The Norwegian herring fishing method has already been 
described. Fig. 17 shows a Norwegian vessel drying up 
a large catch of herring. 

ArraBgemcet: The type of vessel is similar to the men- 
haden steamer, but is wider and deeper. This is because 
there are no draft limitations as in the menhaden fishery. 
The machinery and deckhouse are all astern, similar to 



FISHING METHODS AND PECK ARRANGEMENT PURSJE SEINING 

made additional helper boats are called in to hdp dry up 
the catch (fig. 17). These boats are out on the grounds, 
bang towed by smaUdrifter-lottgltners, The fishermen in 
the helper boats share in the catch that they hdp to dry 
up. The boats towing the helper boats are used to tow 
the "steamer 9 * during hauling and brailing operation. 

Mechanization: The net-handling procedure is little 
mechanized except for some use of powered rollers 
mounted on the gunwhale. The powered block has not 
been tried, and drying up of the fish is done by the use of a 
large amount of manpower in the seine boats and helper 
boats, rather than by the strapping method. The fish 
pump, although it has been tried, is not being employed. 
The method of brailing, using the conventional braiter, is 
well worked out, and good brailing speed is achieved. 
The large and modern "steamers" (seiners) are very fine 
ships, well designed for the system being used. 

Suggested changes: The methods developed in the 
menhaden industry, including the fish pump, strapping, 
and powered block, can be adapted to the Norwegian 
herring boats with very little change in basic system. It 
should be possible to handle the largest sets with the 
above recommended mechanization. Aluminium purse 
boats of the design in fig. 16 are recommended for support 
of the powered block if mechanization is attempted. 

Much further experimentation should be made with a 
one-boat system, working in conjunction with carry- 
away vessels. There is no reason why this system, 
properly applied, should not be successful in the Nor* 
wegian herring fishery and particularly fishing in the 
rough weather which has plagued this industry. The only 
two arguments against adopting the one-boat system are: 

It may be hard for one boat to compete in setting 
in the congested areas where there is so much compe- 
tition for a school of fish 

Unsuccessful experiments have been made in 
Norway with U.S. Western one-boat systems. It is 
the author's opinion that these experiments were 
inconclusive, inasmuch as the boats were not 
adequate; nor were the personnel properly trained. 
Considerable improvement has since been made in 
the U.S. Western technique. A seiner of the design 
of fig. 22 is capable of mechanization, and also can 
set in congested areas. A vessel of this type can 
operate in much rougher weather than the open seine 
boats now used. It would travel to the fishing 
grounds under its own power, or could be towed, 
winched tight to the stern of the carry-away vessel 




Fig. 17. Norwegian herring seiner and seine boats with helpers 
drying up herring for or ailing 

the schooner or cutter design from which they evolved. 
The two purse boats are carried in davits aft. 

Seine boats: Norwegian seine boats are now being built 
primarily of steel A number of aluminium seine boats 
were built without too much success, primarily because 
they were of light gauge, riveted construction. With the 
newer aluminium alloys and welding techniques, alu- 
minium seine boats should have the same advantages as 
observed in the menhaden industry. The Norwegian 
seine boats are arranged with the engine in the stern, and 
the net handling in the bow. They are of whale boat type 
about 32 by 8 ft. (9.75 by 2.44 m.). There is considerable 
difference of opinion as to whether this is a more satis- 
factory arrangement than that used in the menhaden 
seine boats where the engine is in the bow. 

M*ho* affehtag: The echo sounder is used to locate 
the fish, which we very rardy visible on the surface. The 
two purse boats encircle the fish, and when large sets are 



A few years ago purse seining was introduced in Lofoten 
in northern Norway for codfish. Sunken nets were used, 
similar to the U.S. Western purse seining system. These 
nets were handled on the stern of drift-net and longtine 
vessels which were not designed for, and were very in- 
convenient for use with, this system. Purse seining of cod 
in Lofoten, which was found to be very effective, hat 
now been banned by legislation due to conflict with the 
fishermen using traditional methods. 



[43] 



PISHING BOATS -/Of* THE WOftiO : 2 < TACTICS 



Aa experimental powered Mock was introduced into 
that fishery in 1958, and proved an immediate success. 

Staqgotai chnfet: It is suggested that new vessels have 
the deckhouse moved forward, such that the net can be 
efficiently handled using the powered block. The vessels 
now being used are exceedingly inconvenient for purse 
seining* The UJS. Western-style combination purse 
seiners might be ideal for the cod and saithe purse seine 
fishery, and they can also be used for trawling and long- 
lining at other times of the year. 



UNITED STATES WEST COAST, ALASKA 
AND CANADA 

The types of vessels used have been exceedingly well 
described by Hanson (1955). These vessels are used for 
purse seining salmon, herring, sardines, anchovies, 
mackerel, and tuna. 

Arrafeffient: The general arrangement places the 
engine in the bow, with a forecastle for the crew in the 
smaller vessels just forward of the engine room. The 
deckhouse is forward, and is either of the 1- or 2-level 
type. This leaves the large deck area at the stern available 
for handling the net both in setting and hauling. The 
larger boats have all of the crew accommodations in the 
lower deckhouse on the main deck. These quarters are 
spacious compared to European standards, and are very 
comfortable, even in a seaway. The boats are equipped 
with a large mast and boom, and all operations requiring 
physical effort are handled by power, with much use of 
the boom and in some case, booms. 

In this design, a horseshoe, or transom, stern is used, 
with the deck being kept very wide aft, to give a maximum 
amount of stability, working space, and flotation. The 
wide deck aft is very important. The fish hold is placed 
with its centre of gravity on the centre of flotation such 
that the vessel does not trim by the bow or stern when 
loaded. The rudder is kept underneath the counter, to 
keep the net from fouling. The seagoing characteristics 
of these boats are good, and pitching is very small because, 
with the wide stern, the tendency to "hobby-horse" is 
minimized. The tanks are placed in the stern and engine 
room. The forefoot is fairly deep, which keeps the bow 
from drifting unduly. This gives an added advantage, in 
manoeuvring as the stem pivots about the bow, which is 
very convenient particularly when this type of boat is 
being used for longlining. 

Method of fishing: The method of fishing has already 
been described in this paper and, whereas the size of 
vessel and details of the net vary considerably for different 
types offish, the general system is the same for all of the 
types of fish mentioned above. Specific differences will be 
listed below. 

Mechanization: In general, the U.S. Pacific Coast 
boats are mechanized, with the use of the powered block 
and increasing use of wire drum winches for handling the 
purse line. Hie fish pump is little used as yet, because it is 
not applicable to pumping salmon or tuna, which have 
been the primary source of income in this area. Maximum 




Fig. 18. Salmon purse seining on the U.S. Pacific coast set ting 
the net 

use is being made of hydraulic topping lift winches for the 
boom, boom vanging winches, and other mechanical 
aids. Very little physical effort is required by the fisher- 
men. 

Suggested changes: Since the powered block is generally 
used in this area, the requirement for the seine table, as 
shown in fig. 20, and by Hanson (1955), has been 
eliminated. Many of the boats are now removing the 
seine tables, and new vessels are being built without them. 
Since web pulling is no longer done by hand, it is sug- 
gested that the boats be designed with higher freeboard 
and more sheer up in the stern. With the use of the seine 
table, it was necessary to keep the sheer very flat so as 
not to cock the table unduly, and to keep it from being 
excessively high. Increased mechanization of the boom 
should be used, together with more use of auxiliary 
booms for brailing. Further improvement should be 
made in methods and equipment for handling wire purse 
line. The use of aluminium should be adopted in seine 
skiffs. The trend toward excessive beam should be 
stopped. The Alaska limit law, limiting the length of 




Fig. 19. Hatting 300 fm. (550 m.) net with powered block using 



[44] 



FISHING METHODS AND DECK 



ARRANGEMENT PURSE SEINING 




Mom 



LOA 
L 

Ltngth rtgisttrtd 
B 

B*om ovtr guords 
T 

T, fully loodd 
FMS! oil copocity 
i wgtt r capacity 



5783ft(l766mJ 
54 - ft (1676m) 
4992 ft.(tt.l9mj 
1733 ft. (528m.) 
17.92 ft. (5,46m) 
775 ft. (2.36m) 
950 ft. (2.90mJ 
6000001(22680 
l200gol(4630U 
260ip.Continoyi) 





Fig. 20. Modern Alaska limit steel seinerarrangement shewing seine tobk (tables - 
becoming obsolete on vessels equipped with powered blocks) 

[45] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



vessels to 50 ft (15.3 m.) has caused designers to buitd 
wider and wider vetaels. It has been found that beams in 
excess of 1? ft. (5.2 in.) on a 50 It (15.3 m,) registered 
length cause excessive steering problems when driven at 
high speed-length ratios. It is suggested that lower 
deadrise be used with the resultant increase in midship 
coefficient and decrease in prismatic coefficient. The 
tendency in the past has been toward excessive deadrise 
and high prismatic coefficients, which give high resistance 
per ton of displacement. 

Salami 

Fig. 18 shows a typical Alaska limit salmon seiner making 
a set. Fig. 20 shows the arrangement of living quarters, 
working space, winch, and hold. In 1958 this vessel 




Fig. 21. Alaska limit salmon seiner 

covered 17,000 miles in its quest for salmon and sardines 
from the Bering Sea to southern California. The 
Alaska limit design has developed an exceedingly high 
displacement-length ratio vessel, which provides a very 
stable working platform. These are big vessels for their 
length, being designed to make the most of the length 
limitation. The seine skiff will be noted in fig. 18. These 
skiffs are from 16 to 18 ft. (4.9 to 5.5 in.) in length, and 
powered with engines of from 100 to 165 h.p. Their 
primary purpose is to tow the end of the net while the net 
is being set out, tow the vessel away from the net during 
the pursing and hauling operation, and tie off to the 
cork line during brailing. There are probably nearly 
1,000 boats of this general style on the West Coast, 
including British Columbia. Fig. 22 shows a small, 
shallow draught "beach" seiner. From 400 to 500 of these 
vessels operate in the Kodiak Island and Prince William 
Sound areas of Alaska. A vessel of this type carries a 
crew of four, who live aboard. The dimensions are 
39 x 14x2 ft (11.9 x4.3xO.6m.) draft. In Canada and 
on Puget Sound larger purse seine vessels are also used, 
because there is no limit on length, the design 'and 




Fig. 22. 39x14 ft. (11.9x4.3 m.) shallow-draught steel salmon 

seiner, powered with 150 h.p. diesel. Several hundreds of these vessels 

fish the shallow areas of Alaska 

arrangement are similar to the smaller vessels, as shown 
by Hanson (1955). 

The salmon purse seiners have converted generally 
to the powered block, with the exception of some 30 
vessels equipped with drums. Pursing is done, in most 
cases, by a purse winch with two winch heads, using 
manila or nylon purse line. Wire purse line is being used 
increasingly by the bigger boats, using drum type winches. 




Fig. 23. 



ling 400x45 fa. (732x82 m.) 



net. Large am of*p to 300 torn can At Mid up with the smatl crew 
and a powered block. Normal crew is eight \ 



1*6} 



FISHING METHODS AND DECK ARRANGEMENT PURSE SEINING 




Fig. 24. California!* sardine seiner, loaded 




Fig. 23. TtoM *wr converted from CmHfrrnian bait boat,, kafgng ***>/>". <** 
tuna Mines with total erew of 12 men. 11**e venela fi?*"* *** 



7 It currently the moat productive /.S. mrtAorf of producing tuna. Stern view ofSmnt* 
. /Jtf x J0x /*>. W/.*x PJx*J m.) MM MMT of 3SO-t<m capacity, 



ha*Hnf giant net 
with powered Mock 

[47] 



FISHING BOATS Of TKE WORLD ; 2 ~ TACTICS 



Fig. 23 shows a herring vessel These vessels also fish 
salmon during the periods of the big runs. The herring 
vessels in general are largDr from 75 to 95 ft. (23 to 
29 m.) in length. The characteristics of the Pacific 
herring are very similar to that of the herring in Norway. 
The big herring fishery is in British Columbia in the 
middle of the winter. The Canadian herring seiners are 
completely mechanized, using wire purse line and power 
blocks. Sets as large as 500 tons can be handled, drying 
up the fish with the powered block. This has been a big 
improvement in the method of drying up the set. A crew 
of eight men is used, including the captain and man in the 
skiff. Echo sounders in small boats are used to locate the 
herring schools as in Norway. 

Tana 

Tuna seiners are getting larger with the conversion of the 
bait boats to seining. Pacific Fisherman, June 1959, 
describes the economic reasons for the change from pole 



of the coast. Therearenowabout50Qpurscscinersin Peru, 
which has developed its fishing industry most rapidly. 
Purse seining for anchovies in that country may reach 
one million tons in this coining year. The design of 
vessels was originally based on plans by H. C. Hanson, 
and in general follows designs of the Northeast Pacific 
Coast. In the last three or four years, as the industry has 
matured, there has been evolution developing distinct local 
characteristics. In the last two years, the quality of con- 
struction has improved, and the size of the vessels is 
gradually increasing. Those vessels catching skipjack 
tuna are primarily U.S. built. 

Arrangement: Fig. 28 shows a design by the author's 
Compan^pf an anchovy-bonito seiner, typical of modern 
contraction* "in Peru. The arrangement is in general 
similar to that of the Pacific Northeast boats; however, 
the vessels are designed with much greater freeboard 
and carrying capacity for their length. The accommoda- 
tions and rigging of these vessels is very simple. 

Fig. 27 shows a boat designed by the author's Company 




Fig. 26. Side view of Sun King completing broiling ' 



fishing to purse seining. Of primary importance has been 
the Puretic power block and the nylon seine. The tuna 
seines are up to 450 by 50 fm. (825 by 92 m.) and are 
exceedingly bulky. Cotton tuna seines seldcm last more 
than a year. The life of nylon is not known as yet, but is 
probably in excess of four years. The old method of 
strapping the net was slow and tedious. With the con- 
version to nylon, powered block, and other hydraulic 
equipment for handling purse lines and boom, the 
efficiency of the tuna seiner has nearly doubled. Fig. 25 
and 26 show these large purse seine vessels. It is necessary 
to handle all phases of this operation by power equip- 
ment, otherwise the system would not be feasible. 

WEST COAST OF SOUTH AMERICA 

Purse seining on the West Coast of .South America has 
been increasing rapidly. The types of fish obtained are 
anchovies in Peru and northern Chile, bonito in Equador , 
Peru and Chile and skipjack and yellowfin tunaalongmost 



for combination fishing for hake (merluzza) and sardines 
on the West Coast of South America. The deckhouse is 
considerably smaller than would be used in North 
America, and simplicity throughout has been the require- 
ment. Carrying capacity is exceedingly important, and it 
can be seen that the fish holds are proportionately much 
larger than those currently being used in Europe or in 
North America. It will be noted that the seine table, 
which has been common in the Pacific Northeast, has 
been eliminated from these designs, as it is not necessary 
with the powered Mode. It is, therefore, possible to use 
more sheer in the stern of the boat, which gives the after- 
deck ample freeboard when the vessel is loaded, assuring 
safety and stability . 

Method f Mi*: The general method of fishing is 
similar to that used on the U.S. West Coast and Canada. 
Distances to the grounds are very short, and in most 
cases the vessels return before dark. Anchovy, the main 
species fished, is very easy to catch. 



[48] 



FISHING METHODS AND DECK ARRANGEMENT MffKSB SEINING 



Meduudzattoa: The only mechanization is the powered 
block, although a few boats have converted to wire purse 
line, and the fish pump is receiving its initial installation. 

Suggested changes: The size of the vessels will increase, 
probably until they have a hold capacity of about 80 to 
90 tons. Increased use of wire purse line, and the powered 
block, is recommended, in addition to the use of fish 
pumps. In certain areas where the fish are very plentiful, 
carry-away vessels should be adopted, and then the size 
of the seine boat can be held at from 50 to 60 ft. (15.3 to 



described above. Recently, because of manpower short- 
age, the one auxiliary seine boat method is being used, 
towing the single net boat alongside the larger vend. 

Suggested dumges: There is interest in vessels which 
can fish the large schools of herring which have been 
found in the winter close to Reykjavik. New vessels can 
be developed to accomplish this fishery. Fig. 29 and 30 
give designs of two such vessels proposed by the author. 
In addition to being efficient purse seiners, the raised deck 
vessel (fig. 29) would be an exceedingly able stern trawler. 



IDA 94.- ft.064tftO 

L 4650ft, 04. 17m.) 

B !650f1(S03*>) 

8m ov*f guordt 16.83ft ( 5 13m.) 

f,min.dMi9n) WL 358 ft ( 1.09*0 

A, 4L- torn 

HoUoopooty 4O-tpn 

Kfc tood 10- ton 

I, of SOton lood ' 5 - in. (CTtm) 





Fig. 27. 54 ft. (16.5 w.) steel combination trawler-seiner for West Coast of South America, 
designed for trawling hake and seining sardine 



18.3 m.) in overall length. Catch per man in Peru is 
higher than in any other purse seine fishery, even though 
the industry is only eight years old. 

ICELAND 

Arrangement, method and mechanization: The Icelandic 
purse seine fishery is for herring. Originally the system 
was identical to that used in Norway. The method of 
purse seining in Iceland is undergoing change, as 



The compromise design (fig. 30), places the deckhouse 
and machinery amidships. This was done to allow work- 
ing space forward for handling longlines and drift-nets, 
A modified design is proposed similar to fig. 30, but with 
the deckhouse located off centre, allowing 8 ft. (2J m.) 
of working space adjacent to the amidships deckhouse. 
This would be convenient for handling drift-nets. The 
space aft of the deckhouse on this design is amide for 
efficient handling of a purse seine. The drum-type purse 



[49] 



FISHING BOATS OF THE WORLD : 2 TACTICS 







; ' *' t^._. ~l_ x 



o a * on 

I '.''' * t 

O I 25m 




28, 6Q ft. (18-3 *n.) anchovy-bcmito /uirjrr je/wrr >br WV^/ Coast of South 




FISHING METHODS AND DECK ARRANGEMENT PURSE SEINING 



Gmwol 



LOA 
B 



81.5ft. (24.64m.) 
220ft. ( 6.71m) 

T I0.0ft.< 3X>5nO 

Futl copocity 8000 got. 

CJiiNtd woltr cop. 8Oton 

Hold capacity BOton* 




AP WTB WTB 



Wottr- tight 



WTB 



Portable 
trow I goltew* Pond S 





Flf. 29. Proposed combination vessel for Iceland. 140 ton capacity raised deck combination trawler-purse seiner 



[51] 




WTfl 



Wotr tight bufetwod 

LOA 80ft.(243em) 



WTB 




ouhe longhnt gurdy 



N. PUTM dovit 
P ond S 



"Eftgiru "room" SSrtoy| ft? 
P MI s v / 




Fig. 30. Proposed combination vcs&lfbr Iceland* 200 ton capacity compromise design purse seiner-trawler, longltner, and drtfter 

[52] 



FISHI1*G METHODS AND DECK ARRANGEMENT PURSE SEINING 



winch is also designed to handle the trawl cables, so that 
one winch suffices for both operations. Maximum use of 
compact, high-pressure hydraulic winches is made on 
the booms. Fish pumps would be used for unloading 
the net, which would allow extremely rough weather 
fishing. 

SOUTH AFRICA AND SOUTH WEST AFRICA 

In Walvis Bay of South West Africa, and St. Helena Bay 
of South Africa, exist two of the most fabulous purse 
seine fisheries in the world. These fisheries are limited by 
quota to a total of 500,000 tons fish production per year. 
This is accomplished with high tonnage per man efficiency. 




Fig. 31. Typical deck arrangement, South African lampara seiner 

This is partially due to the large concentration of avail- 
able fish, and partially to the unique system used. Fig. 31 
shows the arrangement of South African-type vessels. 
The vessels have evolved from the European drifter type; 
however, they are being built with much more freeboard 
and beam than is common in Europe. A South African 
vessel of 60 ft. (18.3 m.) in length will carry, with deck 
load, well over 100 tons. No other fishing vessels have 
been built which will safely carry as large a load for a 
given length. The arrangement of the vessel is satis- 
factory for the small lampara net used. If the nets were 
larger, the location of the deckhouse in the stern would 
be a handicap. 

Arrangement: The engine is in the extreme stern of the 
vessel, with a huge fish hold forward. The purse winch is 
located just forward of the main deckhouse, and on an 
angle. Rollers are used on the gunwhale, over which the 
purse line leads. These rollers cause an undue amount of 
wear, and should be improved. 

Method of fishing: The lampara net described by du 
Plessis (1959) is handled very rapidly by from eight to ten 
men. The vessel sets with a small skiff tied to the end of 
the net, and on completion of the set pursing starts 
immediately, and the wings are also pulled in partially 
while pursing is in process. This is possible because the 
purse line takes the strain, and allows easy hauling of the 
wings. The echo sounder is in general use in South 
Africa, and in the last two years large quantities of fish 
have been found at times and in areas where there was 
no previous fishing. 

Suggested cbaages: As yet, the powered block has not 
achieved much success; however, proper experiments 



have not been made. Fig. 7 suggests a method of using 
the block. With the use of the powered block and snap 
purse rings, possibly two men could be eliminated from 
the crew, and the work made easier and faster. Further 
experimentation should be made, using a net with the 
bunt at the end, rather than the lampara style with the 
bunt in the middle. Unsuccessful U.S. Western-style 
vessels have been built and tried in South Africa. These 
vessels failed because the design was not correct for the 
local conditions. It is the author's opinion that a 
correctly-designed U.S. Western boat could be developed 
for the South African fishery that would be able to handle 
larger sets as rapidly as the present boats are handling 
small sets, with approximately the same number of men. 
Much criticism is heard in South Africa of the Western* 
designed boats, which apparently cannot carry as big a 
load as the South African design. This, obviously, is gener- 
ally a matter of beam, length, and freeboard in the light 
condition, and the correct U.S. Western design would be 
able to pack as much fish as the South African counter- 
pan. The present South African design and hand method 
of hauling cause severe limitations on the depth of the 
net, as well as the length. With the echo sounder, more 
and more fish have been found at depths for which the 
present lampara is not efficient. Considerably more 
experimentation in basic systems would be desirable. 

The addition of fish pumps on carry-away vessels 
could increase the productivity of the catcher vessels. 
This would allow greater production, with fewer catcher 
vessels and fewer fishermen on the grounds, because it 
would eliminate the waste time of running to and from 
the factory and waiting for unloading. The catcher 
vessels could be mechanized for handling larger sets, 
which would be aided by the fish pump. 



PORTUGAL, FRANCE, SPAIN AND 
NORTHWEST AFRICA 

Sardines 

Sardines are the primary fish purse seined in these areas. 
Arrangement of the boats is shown in fig. 32. As the fish 
are not schooled up very heavily, large nets are used and 




Fig. 32. Typical deck arrangement, Portuguese sardine boat 

the catch per set is small. The vessels have a very small 
fish hold space, and generally the small catch is carried 
on deck. The arrangement of the vessels is only satis- 
factory for hand hauling, with the use of a large amount 
of manpower (25 to 40 men). 



153] 



FISHING BOATS OF THE WORLD : 2 - TACTICS 



The general method was described at the 
beginning of this paper. The boats are well built and sea- 
worthy, and the nets are relatively long and deep. 

Mechanization: The use of the fish finder is highly 
developed, and has increased the productivity of the 
fishery, allowing the boats to fish in the daytime, as well 
as at night, and on schools of fish that are not ordinarily 
visible. This is the only mechanization in the fishery. 

Suggested cfcMpit Manpower efficiency is very low, 
and pay for the crew is small In the author's opinion, 
a U.S. Western-style purse seiner of equivalent size could 
catch an equal amount offish with one-fourth of the crew 
presently used. 

The general system is good, and Portuguese fishermen 
are extremely hardworking. Mechanization would in- 
crease their efficiency. 

Twa 

There is an increasing interest in purse seining tuna in 
France, Spain, Portugal, and Northwest Africa. This is 
partially based on the success of this method in southern 
California. The California vessel design is recommended. 
There is now considerable bait fishing in these areas, 
using modified California techniques. 



ANGOLA 

The methods of fishing in Angola are the same as in 
Portugal, but the concentrations offish are much larger. 
This is a major purse seine fishery, and reduction 
industry. The principal catch is mackerel and pilchard. 
Suggested changes: There is far more reason to change 
the design of boats than in Portugal, because of the large 
amount of fish that are handled. Likewise, there is a 
shortage of trained crews, and the use of more mechaniza- 
tion, including the powered block, wire purse line, and 
fish pump would increase productivity. It is interesting 
to note that the Angola fishery, which is very close to the 
South West African fishery, uses the U.S. style net, 
rather than the lampara. More experimentation should 
be done to determine the relative efficiencies of these two 
systems, and to develop better deck arrangements and 
vessel designs in order to mechanize the best system for 
the type of fish available. 



JAPAN 

Purse seining in Japan is one of the major types of fishing 
methods. The publication, Illustration of Japanese Fish- 
ing Boat and Fishing Gear (1959), portrays pictorially the 
types of seine boats and gear used in Japan. Purse 
seiners are used primarily for mackerel, sardines, and 
skipjack. Japanese boats are of the following types: 

AwVMMMit seiner 

These are wooden boats of 20 to 50 gross tons, operating 
in pairs. The engine room is amidships, with hold 
forward and crew's quarters in the stern. Deckhouse with 



upper pilot house and flying bridge on top are located 
amidships. Purse winch is located forward of deckhouse. 
The net is stacked on the stern. 

These boats work in pairs separating to set the net 
around the fish. A V-sheave manually operated net 
hauler is located on the stern. The net is pursed in the 
normal manner, and half the net is hauled aboard the 
stern of each vessel. 

The vessels are diesel powered and are equipped with 
fish and direction finders, wireless telegraph, and equip- 
ment for determining seawater temperature. Brailing is 
with conventional brailer. 

These vessels are gradually being converted into one- 
boat seiners. 



Two-boat "Aguri" i 
These are small, Japanese-style vessels of 10 to 50 tons, 
of historic design. Although these boats were very 
numerous in the past, they are being replaced by more 
modern vessels. 

One-boat seiner 

These are boats, mostly built of wood, from 60 to 85 tons 
capacity. The trend is to steel construction. Engine room 
is amidships, with hold in the bow. Crew space is in the 
stern. These vessels are of modern design and con- 
struction. 

The method is similar to the U.S. Western purse seine 
technique, with the net stacked on the stern. Pursing is 
done with a winch, just forward of the deckhouse. The 
crew consists of about 30 men, and net hauling is aided 
by the use of a hand-powered net puller mounted on the 
stern. The powered block has not yet been introduced. 
Pursing is mechanized, using wire purse line and net 
reels, similar to the system illustrated in fig. 8. The 
vessels are diesel powered, equipped with wireless, tele- 
graph, and fish and direction finders. 

The one-boat seiner resembles the two-boat seiner, 
although it is generally of more modern construction and 
equipment. The one-boat seine fishery is carried on with 
the help of a fleet of 5 or 6 boats: one or two lighting 
boats, one fish finder boat, one skiff, and one or two fish 
carriers. In this respect, this is an operation of fishing 
vessel with separate carry-away vessels; therefore, the 
fish hold in the catcher boats is relatively small. 

American-style purse . 

American-style purse seiners were introduced into Japan 
immediately after the war. Although the general arrange- 
ment is very similar to the traditional one-boat seiner 
boat of Japan, the details of U.S. construction and 
arrangement were not well accepted and this general 
arrangement is not at present being built. The basic 
difference seems to be that even though the Japanese use a 
partially mechanized system, approximately 30 men are 
needed, resulting in extremely large crew quarters and 
correspondingly small fish hold. The U.S. vessels intro- 
duced were designed for the small U.S. crew, and the 
crew quarters are inadequate for the larger Japanese crew. 



[54] 



FISHING METHODS AND DECK ARRANGEMENT PURSE SEINING 



KOREA 

Modern purse seine vessels in Korea are very similar to 
the Japanese one-boat system. Very large and deep nets 
are used in fishing mackerel in Korea. Recently powered 
blocks have been introduced on the Korean boats, with 
much success, in conjunction with the U.S. International 
Cooperation Administration program. 

U.S.S.R 

A Russian publication (Anonymous, 1958) gives an 
excellent pictorial representation of Russian fishing 
vessels. This publication shows purse seiners of types 
similar to the U.S. Western style, complete with seine 
table, showing methods of handling the nets similar to 
the Western technique. The two-boat system for catching 
herring is also used. 

CONCLUSION 

The percentage of fish caught by the purse seine method 
in world fisheries is increasing rapidly. Great improve- 



ment has been made in some areas in the last few years in 
both method and vessel design. Unless superseded by 
some completely new system such as electrical fishing, it 
is anticipated that purse seining will be applied to more 
and more species of fish in more of the areas of the 
world, and will continue to account for a larger per- 
centage of the total fish production. Nylon nets and 
mechanization of the entire procedure have resulted in 
large increases in man productivity. In many areas the 
traditional designs of vessels should be re-analysed in the 
light of these recent developments. It is most important 
to design the vessel to suit an efficient method rather than 
adapt a method to suit existing designs. 



Acknowledgments 

The author would like to acknowledge assistance in the preparation 
of this paper to : Helge Kristensen for preparation of the drawings 
and diagrams; Dayton L. Alverson, of the U.S. Fish A Wildlife 
Service for helpful suggestions and criticism on the text; and the 
Pacific Fisherman Magazine tor permission to use several of the 
photographs appearing in the paper. 



[55] 



DRIFT-NETTING: DECK DESIGN AND EQUIPMENT 

by 
J. G. DEWIT 



Drift-netting has the advantage that it can be done by boats that have engines with an output as low as 80 h.p. but drifters are 
normally equipped with 150 to 180 h.p. to provide reasonably free running speed. The disadvantages are the rather passive character of 
the fishing method, the high cost of the gear and its upkeep in shore establishments, and the limited duration of the season about eight 
months a year. 

There are two types of arrangement for the drift-net: shallow-water and deep-water. In the former the net is above the warp, 
whereas deep-water nets lie below the warp. Every fleet of nets consists of 100 to 120 separate nets, each 69 to 87 ft. (21 to 26.5 m.) long, making 
the total length about 1.13 to 1.43 nautical mites (2,100 to 2,650 m.). Setting is somewhat different for the two types but hauling is almost the 



The design of a boat is mainly determined by the methods of setting the nets and hauling and processing the catch. About 1 18 ft. 
(36 m.) LBP is considered as the upper limit for a drifter. The prospects for drifting are uncertain due to the disadvantages mentioned and the 
poor results obtained in recent years. The solution for these difficulties may be a combined type of "drifter-trawler". 



EQUIPEMENT DE PONT POUR LA PECHE AUX FILETS DERIVANTS 

La peche aux filets derivants offre I'avantage de pouvoir etre pratiquee par des bateaux dont la puissance des moteurs n'est que 
de 80 c.v., mais normalement les drifters sont mums d'un moteur de 150 It 180 c.v. pour assurer une vitesse de route raisonnable. Les 
inconvenient* sont le caractere assez passif de la methode de pdche, le cout 61cve de J'engin et son emretien dans les etablissements a terre, et la 
duree limitee de la saison de peche environ huit mois par an. 

II y a deux types de disposition des filets derivants: en eau peu profonde et en eau profonde. Dans le premier cas, le filet est au-dessus 
de Taussiere alors que les filets pechant en eau profonde pendent au-dessous d'elte. Chaque jeu de filets se compose de 100 a 1 20 filets separts, 
mesurant chacun 69 a 87 pi. (21 a 26,5 m.) de long et ayant une longueur totale d'environ 1,13 a 1,43 mille marin (2.100 a 2.650 m.). La mise 
a Peau est quelque peu difterente pour les deux types mais k relevage est presque le m6me. 

Le dessin d'un bateau est determine surtout par les methodes de mise a 1'cau et de relevage des filets et de traitement du poisson, Pour 
un drifter, on consider* que 1 18 pi. (36 m.) Le.pp. est la limite sup6rieure. Les perspectives d'avenir pour la pdche aux filets derivants sont 
incertaines a cause des inconvenients mentionnes et des mediocres resultats obtenus ces dernieres annees. Un type combin* de drifter-chalutier 
pourrait permettre de resoudre ces dimcultes. 



PESCA A LA DERIVA: EQUIPO Y FORMA DE LA CUBIERTA 

La pesca a la deriva tiene la ventaja de que la pueden practicar embarcaciones con motores pequeftos de un rendimiento tan bajo 
como 30 c.v., pero normalmente esas embarcaciones cuentan con motores de 150 a 180 c.v. que les dan suficiente velocidad en ruta. Los 
inconvenientes son el caracter bastante pasivo del meiodo de pesca, el elevado precio del equipo y de su mantenimiento en los establecimientos 
de tierra y la duracidn limitada de la campafia: unos ocho meses al afio. 

Hay dos maneras de calar la red de deriva: en agua somera y en agua profunda. En el primer case la red esta encima del cable, 
mientras que en el segundo esta debajo. Cada andana consta de 100 a 120 panes separados, cada uno de ellos de 69 a 87 pies (21 a 26.5 m.) 
de longitud, que le dan una lon^itud total de 1,13 a 1,43 millas nautkas (2.100 a 2.650 m.). El calamento es algo diferente en los dos tipos 
de pesca, pero el halado es casi identico. 

La forma del barco la determina principalmente el metodo de calamento y halado de las redes y el de elaboraci6n de la captura. 
Unos 1 18 pies (36 m.) de eslora entre perpendicutares se coniidera el limite superior para los pesqueros a la deriva* Las perspectivas de esta 
clase de pesca son indertas debido a los inconvenientes mencionados y a los males resultados obtenidos en los ultimo* afios. La solucidn 
de estas dificultades podria ser un tipo combinado de barco de pesca al arrastre y a la deriva. 



HERRING fishing carried out by drifters in the The conditions and circumstances are apt to change 

Netherlands was of considerable importance in completely in a very short time, and it is difficult to say 

the years just after World War II. Now, due to what will happen next, but the advantages must be 

increasingly bad seasons and the disadvantages of drifters, weighed against the disadvantages. Shipbuilding is only 

there seems to be no future for it. When catches improve, one of the factors to be considered; others are in the 

drift-netting is expected to continue for some years. fields of biology, technology and economics. 

[56] 



FISHING METHODS AND DECK ARRANGEMENT DRIFT-NETTING 



Although electronics help drift-net fishermen to locate 
the shoals of herring, drift-netting remains a passive 
fishing method, in that the vessel after setting the nets 
has to watt for the fish to swim into them. 




Fig. 33. Shallow water type drift nets or Scottish 
nets, hung above the warp, are supported by cork 
floats connected to the upper spear line and the buoys 
or buffs. Suitable when the herring are near the 
surface 

The main advantages of drift-netting are: 

Herring which swim too high for trawling can be 
caught 

Engine power can be as low as 80 h.p., which means 
small capital investment and low fuel consumption 

The main disadvantages are: 

41 The passive character of the operation makes it 
impossible to "hunt" for fish 

The fishing gear is expensive 

Vessels with small engines of, say, 240 h.p., cannot 
be used for other fishing during the off-season 
approximately, from January until the second half 
of May 

Fishing gear 

There are two types of arrangement for the drift-nets, 




Fit. 34. Deep-water type drtft nets, hung below the 

cable, suspended from the warp and supported by 

cork floats. Floats are connected to the spearline 

.end by buoys. Used for deeper shoals 



namely, the shallow-water (fig, 33} and the deep-water 
(fig. 34), 

A fleet of nets consists of 100 to 120 separate nets, all 
connected to a warp. The fleet is shot some hours before 
sunset and the drifter is connected to it by a net-swing. 
Hauling begins in the early morning, usually just before 
dawn. 

The deep-water nets are generally used for herring in 
the English Channel and on the Dogger Bank and are 
made of No. 30/15 American or Egyptian cotton; 
whereas the shallow-water nets are of No. 30/12 or 36/12 
cotton. The seizings are generally of manilla, f in. 
(16 mm.) diam. The manilla warp varies from 330 to 
375 Ib. (150 to 170 kg.) per 120 fm. (220 m.). 

The net-swing must be heavier than the warp because it 
has to absorb the forces acting on the fleet, caused by the 
movements of the vessel. Made of manilla, about 450 Ib. 




Fig. 35. Setting of Scottish nets. Fisherman 'A' connects the seizing 
to the warp and fisherman *' the buffs to the spearline 

(200 kg.) per 120 fm. (220 m,), the net-swing is about 
75 fm. (137 m.) long in strong winds, but may be less 
when the weather is fine. 

Setting the nets 

Setting a fleet of 100 nets takes 1 to 1J hrs. With 
shallow-water nets, the warp from the rope room runs 
over a fairlead on the starboard bulwark as it passes 
overboard, as shown in fig. 35 and 36. Fisherman A 
connects the seizings to the net at the marked places. 
Fisherman B connects the buffs to the buff strops on 
the float-line, the buffs being brought by a boy from the 
buff store forward. 

The warp of the deep-water nets is carried forward 
from the rope room over the deck and passed overboard 
just behind the forecastle, as shown in fig. 37. At the same 
time the nets are run out over the rollers fitted on the 
starboard bulwark just abreast of the net hold. While the 
boat steams very slowly astern, steered with a bow 
rudder, fisherman A passes the seizings to B, who takes 
them forward to C, and he in turn connects them and the 
buffs to the warp. 

When the setting is finished, the net-swing is led 
through a deep fairlead just abreast of the stem and 
fastened to a bollard, located between the foremast and 
the hawse. This fairlead is usually made of cast iron and 
has sufficient depth to prevent the net-swing from 
slipping when the vessel pitches. 

Circular hawses are used on vessels with an open 
forecastle. To keep the space under the forecastle as dry 
as possible, the hawses are closed with a plate when 
sailing. 



[57] 



FISHING BOATS OF THE WORLD : 2 TACTICS 




Fig. 36. Setting of Scottish nets abreast the net room. The warp 
runs from the fairlead on the bulwark forward to the watertine. 
The buffs are in the pond, ready to be connected to the upper spearline. 
The skipper, on the bridge, overlooks the operations, while manoeuv- 
ring his vessel slowly astern downwind. 
(Courtesy N. farlevtiet Jr., Katwlfk an Zee) 

The mizzen sail keeps the bow of the vessel to the wind 
when drifting with the nets set out. The wind pressure 
on the vessel is normally enough to keep the warp 
stretched. In strong winds the main engine is put "slow 
ahead 9 ' to relieve the strain on the net-swing. A con- 
trollable-pitch propeller is better for this operation, 
because it allows the engine to run at optimum and 
constant speed. 

Hauling the nets 

The warp is hauled in by the winch. Hauling cause* the 
ship to move slowly in the direction of the fleet. To 
relieve the strain in strong winds the engine is run "slow 
ahead". With shallow-water nets, the fisherman at F in 
fig. 38 disconnects the net seizings from the warp, and 
the outboard hanging nets, with the buffs are taken aft 
to the net roller. The man at L disconnects the buffs 
from the strops as the nets come over the roller, while G 
clears the seizings as they come in. 

The nets are hauled by the men at A, B, C, D and E, 
who shake them up and down at the same time to empty 
out the herring. The fish fall into the pond H to starboard 
and into the space between the two ponds, stow boards 



being used to prevent them from scattering over the 
deck. 

Hauling a fleet of deep-water nets differs only in that 
the buoys are disconnected at G. This is not difficult on 
ships which have no forecastle. When there is a fore- 
castle, the circular warp hawse pipe is usually not wide 
enough to take the buoys, so the buoy ropes are dis- 
connected from the warp at F and fastened to an endless 
rope, running through the hawse and around the back of 
the forecastle. 

The hauling gear is shown in fig. 39 and 40. Until 
some years ago the nets were hand-hauled, but now 




Fig. 37. Setting of deep-water type drift nets. The warp goes over- 
board almost abreast of the fore mast. The nets are abreast of the 
net room. The seizings are taken to *C" by fishermen *A* and *B\ 



net room. The seizings are aen o y sermen an 
The buff strops or buoy ropes and the seizings are connected to the 
warp at 'C' 

power rollers are used. These power rollers cause 
problems regarding the safety of the deck-hand at M. 
This deck-hand, who controls the hauling speed of the 
warp, is a boy of 14 or 15 years, usually the youngest on 
board. There is an historical reason for entrusting this 
work to a boy; when the warp was hauled by a hand- 
driven capstan, it was a boy's job to haul off the warp 
from the capstan while the crew "walked" around. 
Differences in hauling speeds of nets and warp were 
adjusted by slower hauling of whichever was ahead. 
When the steam capstan was introduced, the hauling 
speed was controlled by the boy, or the skipper on the 
bridge, by regulating the steam flow to the winch. 




Fig. 38. Hauling. The warp rests in the hawser abreast of the stem. 
The propeller turns at a very low r.p.m. to maintain a balance between 
a sufficiently tight warp and too strong a pull. The seizings are dis- 
connected at 'F' and tfte buffs or buoys at *L 9 or *G'. Fishermen 'A* 
to *' are pulling in the net and shaking the herring into the pond *#*. 
The nets disappear into the hatches *' 

Although modern belt-driven winches are more compli- 
cated and harder to handle, the job is still done by boys. 
Power-driven net rollers, introduced a few years ago, 
have made their work even more difficult. These rollers 
are belt driven by the winch shaft. The hauling speeds 
of the warp and the nets are theoretically the same, but 
that of the warp is greater, due to the slip of the nets over 
the roller. At intervals this inequality has to be corrected. 
This can be done by stopping the winch and slipping the 
necessary length of warp. This is not very dangerous for 



[58] 



FISHING METHODS AND DECK ARRANGEMENT DUIFT-NETTING 

gut, the herring being brought to them from the ponds 
by another gang, who also take the gutted herring to the 
two men who salt them. 

The barrels have to stand for hours and be topped up 
at intervals, before they can be closed, to allow the con- 
tents to settle. When closed they are lowered into the hold 
which is divided into compartments having a width to 
accommodate the barrels lengthwise. In loading a fresh 
compartment all empty barrels have to be brought on 
deck. If each compartment has a central partition, 26 to 
30 barrels are stowed on deck, but when there are no such 
partitions, the deck has to accommodate about 60 barrels. 
Therefore a drifter must have ample deck space forward 
of the ponds to accommodate the filled but not yet 
closed barrels and the empty barrels, yet leave enough 
working space. 

Deck gear 

When setting, the nets are led over rollers on the hatch 
coamings and from there over the shooting rollers on the 
starboard bulwark, and then overboard. The hatch 
rollers are removed when setting is finished. 




Fig. 39. Hauling and shaking. Fishermen are leaning against the 

port pond. Lower left, the fishermen in the net room are hauling the 

nets to the hatch. The nets are led over a roller between the two 

ponds. Buffs are seen in the foreground. 

(Courtesy N. Parltvliet Jr., Katwljk an Zee) - 

the deck-hand at M, but stopping the winch also means 
stopping the net rollers : the crew generally object and the 
boy is strongly urged to slip the warp without stopping 
the net rollers, i.e., without stopping the winch. This is 
very difficult for a youngster to do on the deck of a 
rolling and pitching vessel, and some fatal accidents to 
boys have resulted. In the Netherlands it is obligatory 
that the net roller drive is independent of the winch drive, 
so the deck-hand at M can stop the winch to slip the warp, 
and the powered net rollers continue without interruption. 
The nets pass from the fishermen A to E over an 
athwartships roller, aft of the ponds, through the hatches 
K, into the net room, where they are spread evenly over 
the whole floor. As the nets are easily torn if they catch 
on protruding objects, constant care must be taken to 
avoid such mishaps. 

Processing the catch on board 

The herring are gutted on board and salted in barrels, 
which are then closed and stored as shown in fig. 41. If 
the catch is too large it is salted in an ungutted state, to be 
processed as smoked herring. 

Gutting is done on a bench, forward of the winch, 
which runs. from bulwark to bulwark. About ten men 




Fig. 40. Hauling. The train of buffs can be seen lying In the water* 
The fishermen upper If ft disconnects the sellings. The fisherman 
forward of the pond is holding the upper spearttne and keeping the 
hose seizings clear from the roller. The open barrets contain the 
previous day's catch. The sallow indicates that this vessel is also* 
suitable for trawling. 

(Courtesy N. Parkvtitt 7r, Jtowtf* ah 2**) 



[59] 



FISHING BOATS OF THE WORLD : 2 TACTICS 




fig. 41. After being gutted and mixed with salt, the herring are put 
into the barrels > which have to stand open for many hours to allow the 
contents to settle. The barrels are topped up several times before they 
are closed. The day* scotch is in the pond. The previous day' scotch is 
in closed barrels which will be lowered into the hold and empty barrels 
brought on deck. Drift-net fishing requires ample deck space for 
processing the catch 

At one time the side rollers for hauling had a diameter 
of about 6 in. (IS cm.), but some years ago it was 
increased to about 16 in. (40 cm.) with the introduction 
of the mechanical drive. These rollers are driven by the 
winch shaft running from the front of the engine skylight 
or the superstructure. A pulley is fixed on this winch 
shaft for a belt drive to the rollers. The winches are of a 
simple type and belt-driven from the main or an auxiliary 
engine. The best way to drive the power rollers is an 
arrangement that allows the skipper in the wheelhouse 
to regulate the speed of the net rollers, and to evep the 
differences of the hauling speeds of nets and warp. For 
this, the electric or hydraulic drive appears to be the best 
solution. The long power rollers usually extend beyond 
the ship's side and are likely to be damaged in harbour. 
To avoid this, the rollers are often hinged at a point near 
the deck to allow them to be moved inboard. 

The ponds are nearly the same height as the bulwarks. 
They must be easily removable, especially on vessels 
which trawl during the winter months. Each pond is 
divided into two or three compartments by longitudinal 
boards, which prevent the fish moving about too much 
and thus losing condition when the ship rolls. 



Hauling is preferably done over the starboard side, but 
a shifting wind may make this difficult and bring the nets 
along the stem or even under the keel. In such circum- 
stances the nets are hauled on the port side, 



Because a drifter sets its fleet while steaming slowly 
astern, a bow rudder is required. This is constructed to 
fit well into the form of the hull, as shown in fig. 42. The 
rudder can be settled in the central position by a fixing 
rod while steaming. This rod is located in a pipe and can 
be easily disengaged on deck. The rudder head is carried 
up to a tiller on deck. 

Another type consists of a rudder head resting in a 
heel pot rivetted to the stem as far below the waterline 
as possible. The lower part of the rudder head is square; 
the upper part is kept in position by a bearing. The tiller 
remains outside the bulwark and is operated from the 
deck by two tackles. The rudder plate has two arms 
which fit to the square on the rudder head. A rudder 
davit on the bow enables the rudder plate to be moved up 
and down. Before setting, the rudder plate, pointing 
forward, is lowered. When sailing it is hoisted and fixed 
against the bulwark, pointing aft. 

A mizzen is used to keep the vessel's bow to the wind 
when heaving-to, riding at the fleet and hauling. 

The position of the foremast is determined by the 
loading and unloading gear (de Wit, 1955). There are 
considerable difficulties in stowing and in loading barrels 
forward of the foremast and, for this reason, the best 




Fig. 42. Bow rudder. Its design can be made to fit into the waterHnes 
having a rather sharp entrance angle 



[60] 



FISHING METHODS AND DECK ARRANGEMENT DRIFT-NETTING 



place for the foremast is on, or just aft of, the forward 
hold bulkhead 

Under deck arrangement 

In subdividing the hold, the size of the barrels is taken 
into account. The height of the barrels determines the 
distance of the wooden partitions between the rows of 
barrels. 

A Dutch barrel has a height of 2.4 ft. (73 cm.), whereas 
a Scottish barrel is 2.54 ft. (77 cm.) high. Allowing 2.5 ft. 
(76 cm.) between the partitions for a Dutch barrel and 
4 in. (10 cm.) on one side for the thickness of the partition 
planks with clamps, the neck-to-neck distance between 
the partitions amounts to 2.85 ft. (86 cm.). These parti- 
tions are preferably arranged in steel channels, welded 
to the reverse frames, so that the distance between frames 
is ruled by the distance between the wooden partitions 
or, for Dutch barrels, 17 in. (43 cm.). 

The net room has a length equal to at least five frames, 
namely 7 ft. 1 in. (2.15 m.). The frames are covered with 
wood to prevent the treated nets coming into contact 
with the hull. The location of the net room hatches is 
determined by the location of the aft bulkheads of the 
ponds. The rope room is aft of the winch, with a capacity 
of at least 320 cu. ft. (9 cu. m.) and a floor space large 
enough for coiling down the warp. Lath sheathing is 
normally used on the hull and the bulkheads. 

It is possible to use a double barrel compartment as a 
rope room, in which case its width must be about half 
the breadth of the vessel. As a height of about 8 ft. 3 in. 
(2.5 m.) is sufficient, a fuel oil tank can be installed under 
such a rope room. 

Sometimes the rope room is built into the engine room, 
but this is not recommended because it cramps the 
engine room space. A circular hatch of 2 ft. (60 cm.) 
diam. and a minimum height of 1 ft. (30 cm.) gives 
entrance to the rope room. The hatch is closed with a 
steel lid or a hood of i in. (6 mm.) plate. 

The crew's quarters in older drifters are arranged both 
forward of the hold and aft of the engine room. The 
forward quarter provides room for twelve men and the 
aft quarter for three or four. In modern vessels all crew's 
quarters are located aft of the engine room. The after 
pan of the vessel has a deckhouse which, at least to port, 
reaches to the side. 

Hull form 

For good manoeuvrability when sailing astern, a drifter 
should not have too much trim by the stern. If it does, 
the ship will only respond slowly to the bow rudder. 

When riding to the fleet the forefoot must not be of too 
shallow draught, otherwise the bow will be "thrown 
away" by the swell and the nets may be damaged. 

Dutch driftera of 82 to 98 ft. (25 to 30 m.) LBP have 
the following draughts: 

Forward , 6 ft, 7 in. to 7 ft. 3 in. (2.0 to 2.2 m.) 
Aft . , 9 ft. 2 in. to 9 ft. 10 in. (2,8 to 3.0 m.) 

The bow must not be too high because net damage 
can result from the wind blowing away the bow; nor 



should the warp hawse be too high above water. These 
requirements result in a very moderate sheer forward, 
which also provides a good working platform forward. 

Before 1940 there was a trend to increase the length of 
new ships from 90 to about 105 ft. (27 to 32 m.) LOA. 
After 1945 this trend continued until vessels were about 
1 18 ft. (36 m.) long, which for drift-net fishing, must be 
considered as the maximum. It is commonly considered 
that the sea qualities necessary for drift-netting would be 
lost if this length is exceeded. Experience has shown that 
more net damage occurs when vessels are longer. 

The beam of the older boats is about 21 ft. 3 in. (6.5 m.). 
Just after World War II a drift-netter of 105 ft. (32 m,) 
LBP was built with a beam of 22 ft. 4 in. (6.8 m.). The 
trawler-drifters of about 1 15 ft. (35 m.) LBP, in which the 
emphasis is on trawling rather than drifting, usually 
have beams of 25 ft. 1 in. (7.6 m.), but it is felt that they 
have excessive beam with a correspondingly large CM 
which makes them too stiff. If the GM is too large the 
period of roll will be too short and the barrels on deck 
will he upset. When a ship is built primarily for drifting 
its beam should not be larger than about 23 ft. (7.0 m.). 

The depth of a drifter is generally 10 ft. 4 in. (3.15 m.) 
but sometimes as much as 11 ft. 6 in. (3,5 m.). The 
depth is determined by the number of barrels that can 
be stowed on top of each other without damaging those 
at the bottom: if there is too much pressure the lower 
barrels may spring leaks, especially when the vessel 
pitches and rolls. 

Six layers of deal barrels can be stowed without danger 
to the bottom layer, such stowage requiring a depth of 
10 ft. 4 in. (3.15 m.). With oak barrels, seven layers 
can be stowed and they need a depth of 11 ft. 6 in. 
(3.5 m.). 

According to Roorda (1957) the coefficients of drifters 
should be 8=0.52 to 0.54, p=0.73 to 0.80, 9=0.65 to 
0.74, a =0.83 to 0.86. The floor should rise 3 ft. 3 in. to 
4 ft. (1 to 1.2 m.) and the bilge should have a radius of 
about 3 ft. 7 in. (1 . 1 m.). The hull form must be such as to 
dampen pitching and heaving and the wind profile should 
be kept as small as possible, especially forward. 

The old drifters, which were very good vessels for 
drifting, had a vertical stem with V-frames forward, 
almost without flare, and fine waterlines in which the 
bow rudder fitted well. The raking stem now used has 
not been an improvement. 

Propulsion machinery 

When drift-netting, a ship must be able to steam astern 
for a long time, and when hauling much manoeuvring is 
necessary. To do all this a mechanical or an hydraulic 
reversing gear is much better than a direct reversible 
engine. For the same reason it is desirable to have a 
controllable-pitch propeller. 

The coupling of the engine to the propeller shaft 
usually has no reduction gear. The engines have a 
maximum speed of about 350 r.p.m., bat must be able 
to work for hours at their lowest speed, H* the speed is 
too high and the propeller is engaged when the ship is 



[61] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



hauling there is a great risk that she will suddenly gain 
too much speed. When that happens the warp will 
slacken and the foreship may easily run over the nets. 



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Fig. 43. Trends in drift-net herring fishing. During recent years the 

number of vessels, voyages and days at sea have all decreased; so 

have catches. Catches by trawling are increasing 

The control of the engine and the reversing gear must 
be from the bridge where the skipper can see the whole 
scene. Although one qualified engineer is carried when 
the vessel has an engine of 1 SO to 225 h.p., and two when 
the engine is more than 225 h.p., it is difficult to keep them 
in the engine room during fishing operations. 

Prospects 

As previously stated, the results of drifting in the Nether- 
lands have not been encouraging in recent years, as 
shown in fig, 43 (Jaarcijfers ... 1954 to 1958), although 
there was an improvement in the first part of the 1*958 
season. Drifters are cheap to operate, but they can only 
be used from May until the end of December. This 
creates a social and economic problem because most of 
the crews often remain as idle as their ships. In an attempt 
to solve their problems, engines with higher power than 
is necessary for drifting have been installed, thus bringing 
into being the combined type of "drifter-trawler". 

In recent years, when some drifters have been scrapped, 
the question has been asked: What kind of ships should 
be built in their place to maintain the fishery? That is 
very difficult to determine. Trawlers are increasingly 



supplying the market with sea-gutted, sea-salted and sea- 
packed herring, formerly the function of drifters, and a 
trawler can be used all the year round. 

Again, the fishing gear for drifting is very expensive, 
and a costly shore establishment is needed to maintain it, 
as shown in fig. 44 and 45. Indeed, the cost can seldom 
be borne by owners of only one to three vessels; so the 
trend has been for such owners to sell their ships to 
larger concerns. 

While many factors point towards a disappearance of 
the drifter, herring can usually be caught by drifting when 
bottom trawls produce little or nothing. For this 
reason there is some hesitation in giving a plain answer 
to the question posed above. The trend so far has been 
to replace drifters by small trawlers of 118 to 125 ft. 
(36 to 38 m.) LBP, with engine outputs of 600 to 800 h.p. . 
Most of these vessels are doing very well. There is also 
the trend to combine drifting and trawling, which is not 
a new idea. It has been tried in Germany with the aid of 
the "propeller-rudder". When drifting, this "propeller- 
rudder" only is used, but for trawling or steaming the 
main engine is brought into action. A Dutch shipyard is 
following another method and is constructing a vessel 
of 126 ft. (38.5 m.) LBP, with a twin engine installation 
(2x500 h.p./650 r.p.m.) working on one propeller shaft 




Fig. 44. The shore establishment for the upkeep of fishing gear is 
costly. The fleets of nets can be seen in the background* and targe 
quantities of prepared ropes, etc,, are shown hanging from the ceiling 



[62] 



FISHING METHODS AND DECK ARRANGEMENT DR*IFT-NETTING 



through a 3 : 1 reduction gear. For drifting, only one 
engine is used, but both for steaming and trawling. 

The requirements of a drifter and those of a trawler are 
contradictory in many respects. The modern tendency is 
to give the crew better protection against the weather 
and the sea. This naturally improves the working con- 
ditions and it also increases the efficiency of operation 
and the quality of the product. All these developments 
and improvements might result in a new type of fishing 
vessel. Fig. 46 is a sketch resulting from- some thinking 
about such a new type. 

Trawling is done over the stern. This brings the deck- 
house more forward and gives a reasonable length between 
the slipway and the electric winch. Drifting takes place 
more forward than is usual in Dutch vessels. The net 
room (5) and the rope room (6) are located forward of 
the fish holds (3) and (4). The fish ponds (IS) and the 
capstan (16) are located on the 'tween deck. In this way 
net damage caused by the pitching and heaving while 
hauling can be greatly reduced. Over the ponds (15) 
there is a double deck height for nearly the full breadth 
of the vessel. When the nets are shaken so that the 
herring can fall clear of them, there should be sufficient 
deck space alongside. 

The 'tween deck at the ponds is built about 2 ft. (0.6 m.) 
higher, and the bottoms of the ponds are sloped. This 
slope causes the fish in the ponds to slide astern to sluices 
in the forward bulkheads of the working space, and from 
these sluices they pass to the working space (13) and (14), 
where they are processed. 




Flg.45. 

condition before the ***** starts. Damaged nets are prepared by 

the fishermen** wives while the vessels are at sea. The nets are haded 

on carriages, seen In the background, bid out to dry, thoroughly 

inspected^ and repaired on the spot 



The crew is accommodated in the forward part of the 
ship but the engineers have their quarters near the 
engine room. 

The power units may comprise a main engine of about 
600 h.p. and an auxiliary engine of about 200 h.p. The 




affording more shelter for the 
of the figures: 

HydraulfcaUy-operated bow rudder 

Chain locker 

GaUey and meesroom 

Cook's store 

Starboard: Captain 

Fort: Mate 

Chart room 

Wheelhouse 

HydrauUcally-operated net rollers 

Engineers' cabins 

Boatswain's store 

Engine casing 

HydraulicaUy-operated hatch covers 



Fuel oil 



Fig. 46. Sketch of a trawler-drifter 
crew. Explanation 

1. After peak 17. 

2. Engine room II. 

3. Hold for about 700 barrels 19. 

4. Insulated fish hold 20. 

5. Net room 21. 

6. Rope room 

7. Crew's quarters 22. 

8. Drinking water 23. 

9. Fore peak 24. 

10. Hydraulic steering gear 25. 

11. Fish pond for trawling 26. 

12. Sorting place 27. 

1 3. Gutting and salting 28. 

14. Filling and closing the barrels 29. 

15. Ponds for drifting 30. 

16. Hydraulic or electric capstan 

auxiliary engine drives a generator which supplies current 
to the motor of the electric winch and also to a motor 
mounted on the propeller shaft. The auxiliary engine 
thus serves a triple function: 

It operates the winch 

Through the propeller shaft motor its power can be 
added to that of the main engine for propulsion 
when trawling 

Alone it can drive the ship when drifting, the main 
engine being stopped 

With about 200 h.p. and suitable electrical wiring this 
auxiliary engine should give the vessel good manoeuvra- 
bility for drift-netting operations. 

A vessel like that outlined in fig. 46 might have the 
following main dimensions: 

LBP =118 ft. (36m.) 

B =26 ft. 3 in. (8,0 m.) 

D Ctween deck) = 10 ft. 6 in. (3.2 m,) 
D (shelter deck) = 17 ft. 6 in. (5,3 m.) 
Due to the rather high superstructure forward, a 
mizzen sail will be necessary to keep the vessel in the wind. 



[63] 



GILLNET FISHING: DECK DESIGN AND EQUIPMENT 

by 
THOMAS E. COLVIN 



The Great Lakes (U.S.A.) gillnetter is distinguished by the extensive superstructure which covers the full length of the hull. Climatic 
conditions on the Lakes make this superstructure necessary, which, in turn greatly influences hull design. Hull developments has progressed 
and been refined from early tugboat designs. While the early boats were of wood, the majority of all new construction is of steel. The V-bottom 
has been found to be the most economical method of constructing a steel hull for the Great Lakes. Nets are set from the stern and picked or 
lifted from the bow. These vessels must possess many of the capabilities of the ordinary icebreaker because of wintertime operation. Engines 
today are primarily high or tow-speed diesels; formerly, steam and gasoline engines were popular. Air-cooled diesete show promise. There 
is a possible future development of small gillnettcrs for perch, and they would be about one-half the size of the existing gUlnetters. Wood, in 
all probability, would be used for these smaller boats. 

The fishing industry has declined sharply due to the infiltration of the lamprey eel into the Great Lakes. It has completely destroyed 
trout in Lakes Erie, Huron and Michigan. Because of the lamprey, catches of fish are down from one-forth to one-tenth of what they were 
15 years ago. Part-time fishermen require smaller boats, as the existing boats are too large for present catches. 



EQUIPEMENT DE PONT POUR LA PECHE AUX FILETS MAILLANTS 

Le bateau depftche aux fillets maillants des Grands Lacs (E.-U.) se distingue par ses superstructures ctcnducs, qui couvrent toute la 
longueur de la coquc. Les conditions climatiques sur les Lacs rendent ces superstructures n&essaircs, et a leur tour elles ont une grande influence 
sur le dessin de la coquc. Le dveloppement de la coque a progressed et elle a et affinee a partir des formes primitives de remorqueur. Alors 
que les premiers bateaux 6taient de bois, la majority de toutcs les constructions nouveltes est en acier. On a trouv6 que le fond en V est la 
mfthodc la plus taonomique de construction d'une coque d'acicr pour les Grands Lacs. Les filets sont mis a 1'cau par raniere et ramasses ou 
releves par ravant. Ces bateaux doivent avoir la plupart des capacites du brise-glace ordinaire a cause de la peche en hiver. Les moteurs 
actuels sont surtout des diesels rapides ou lents; auparavant, les moteurs a vapeur et a essence &aient tres itpandus. Les diesels refroidis par 
air offrent des possibility. II sera possible de proc6der au ddveloppement des petite bateaux pechant la perche aux filets maillants, et Icurs 
dimensions seraient environ la moitte de celles des bateaux existants, ptehant aux filets maillants. Scion toutes probability on utiliserait 
le bois pour ces petits bateaux. 

L'industrie de la peche a nettement dtelinl par suite de 1'infiltration de la lamproie dans les Grands Lacs. A cause de la lamproie, 
les pechcs de poisson ont baisst d'un quart a un dixicme de cc qu'elles fraient il y a 15 ans. Les pccheurs ne s'adoimant pas exclusivement a 
la pdche ont besoin de bateaux plus petits car les bateaux existants sont trop grands pour les ptehes actuelles. 



LA PESCA CON REDES DE ENMALLE: FORMA DE LA CUBIERTA Y EQUIPO 

El barco de pesca con redes de enmalk de los grandes lagos de los E.U.A. se caracteriza por su amplia superstructure, que < 
toda la eslora del casco. A emptear estas superestmcturas, que influyen mucho en la forma del casco, obligan las condicioncs climate 



de los lagos. Estos cascos son un perfeccionamiento de los antiguos de los remokadores. Aunque lot primeros barcos eran de madcra, 
todos los nuevos se construyen de aoero. El fondo en V ha dcmonstrado ser el m&odo mas ccon6mk de construir un casco de accro para 
navegar en kw grandes lagos. Los artes se calan por la popa y se recogen por la proa. Estos barcos tienen que reunir muchas de las 
caracteristicas de los rompehielos corrientes a causa de pescar en el invierno, Los motores empleados en la actualidad son printipalmente 
Diesels de alta o ba^a yelocidad; antiguamente eran populares las maquinas de vapor y los motores de gasolina. El motor Diesel enfriado 
por aire ofrece posibilidades. La pesca de la perca es un posible campo de actividades futuras para barcos pequeAos que empkan redes 
de enmallo, pero los barcos tendrian que ser un 50 % mas pequefios que los actuates. Es muy probable que se usase madera en la oonstruccidn 
de estos barcos mas pequeftos. 

La industria pesquera ha dccaido mucho debido a la llegada de la lamprea a los grandes lagos. Debido a lot estragos causados por 
la lamprea, las captures de pescado nan disminuido a cntrc la cuarta y la dcima parte de lo que eran haoe 15 afios. Los Pescadores que no 
dedtcan todo su tiempo a la pesca necesitan embarcaciones mas pequeflas, porque las que tienen actualmente son demasiado grandes para 
las captures que tagran. 



f | *HE Great Lakes (U.S.A.) gillnetter is distinctive 

Iin appearance due to its rather high superstructure, 
shown in fig. 47 and 48. This superstructure has 
greatly influenced the design of the hull and is the result 
of coping with climatic conditions on the lakes. The 
gillnetter is used on all five of the Great Lakes, but is 
most popular and numerous on Lakes Michigan, Huron 
and Superior. Almost every harbour on these three 
lakes on both the Canadian and U.S.A. sides, has a 



small fleet of gillnctters which were originally designed 
to fish trout, perch, chub, whftefish, smelt, salmon, 
suckers, herring, and other species of fresh-water fish. 
These vessels range in length from about 33 to 60 ft. 
(10 to IB m.); and the most common length is between 
40 and 45 ft. (12 and 14 m.), and these are usually 
two-man boats. 

The long superstructure was necessitated by the 
extremely cold weather of 0F ( 18 Q C). There are 



[64] 



FISHING METHODS AND DECK ARRANGEMENT GILLNET FISHING 





Fig. 47 and 48. Great Lakes gillnetters with high superstructure to protect the crew 



relatively few days during the winter when the tempera- 
ture is much above freezing point. The entire interior of 
the vessel is kept warm during the winter by a coal or 
oil burning stove. This prevents the nets from freezing 
and also keeps them dry prior to being set. The fishermen 
are reasonably warm except when actually hauling. 

During the early days, some of the gillnetters had 
split superstructures and occasionally only a forward or 
after deckhouse. Net boxes were carried on deck, as 
were the fish. In the winter it was not uncommon to 
have a large accumulation of ice on the decks, in the nets, 
and in the fish, which caused a severe stability condition, 
so there was always the danger of loss of life and gear 
due to capsizing, even with careful handling. Since these 
boats are also called upon to break ice to get to and from 
the fishing grounds, as shown in fig. 49, conditions were 
aggravated by this accumulation of ice and the weight 
of nets and fish so high above the waterline, especially 
when the hull rode up on an ice floe prior to crushing the 
ice. Also, it is often desirable while going through the 
ice to rock the hull in order to break an even larger 
channel to allow backing, manoeuvring, and gaining 
speed to continue to break ice ahead of the hull. 

The early boats were constructed of wood, and, for the 
most part, were based on the tugboat hull, the only 
difference being in the superstructure. The hulls were 
sheathed with galvanized iron from slightly above to well 




Fig. 49. Greet Lakes glllnetter in Ice 



below the waterline. They were propelled by steam at 
first, but the Great Lakes gillnetters adopted gasoline 
engines very early in the twentieth century. In those 
days, when the fishing fleet was primarily of wood 
construction, the addition of the full-length deckhouse 
often lightened the hulls rather than made them heavier 
through the elimination of the main deck. Superstruc- 
ture framing was widely spaced and lightly sheathed 
with tongue-and-groove ceiling of f to j in. (9.5 to 19 mm.). 
Actually, the only requirement of the deckhouse is that 
it be weatherproof and watertight, and that it supports 
the weight of a man and some light buoys, anchors, and, 
occasionally, some newly-treated nets which would 
present a fire hazard if stowed inside before being set 
the first time. With these deckhouse changes, the net 
boxes were lowered to a working flat. With the intro- 
duction of adequate heaters to warm the whole interior 
of the hull, the nets that had been hauled remained warm 
and did not freeze. With the lowering of the centre of 
gravity, the boats became safer: the fishermen worked 
lower in the boat and were better supported, as well as 
remaining reasonably dry and protected not only from 
the winter cold but from rain and the hot sun of summer. 

Other types of fishing vessels are used on the Great 
Lakes, the design being entirely different from the 
gillnetter. These include the pound-net and trap-net 
boats, which are very popular on Lake Erie, and an 
occasional handliner for trout. 

Fishing gear 

The gillnets of the Great Lakes are normally set on the 
bottom, and vary in length from 1,000 to 30,000 ft 
(305 to 9,150 m.). The lengths are made up into boxes, 
each box containing from 1,000 to 2,000 ft (305 to 
610 m.) of nets, with corks and leads. The nets vary in 
width from 5 to 6 ft. (1.5 to 1.8 m.). Along the upper 
portion of the net are placed aluminium or plastic floats. 
The floats are approximately 4 in. (102 mm.) in length by 
2 in. (51 mm.) in diameter and are spaced from 7 to 9 ft. 



[65] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



(2.1 to 2.7 m.) apart. Opposite each float is a lead of 
approximately 6 oz. (170 g,) which is of sufficient weight 
to sink the net and the floats to the bottom* The leads 
are of cylindrical shape about 4 in. (102 mm.) in length, 
with a hollow centre, and are so tied as to permit them 
net only to revolve but to move slightly back and forth 
so that there is no binding while being pulled around the 
lifting drum. The mesh is about 2.5 in. (64 mm.), 
although this differs greatly from State to State. The 
nets are of nylon. The seaming twine is of cotton. The 
float and lead lines are of linen or cotton, and occasion- 
ally nylon thread consisting of three or more strands, 
specially treated by dipping in a preservation made of 
gasoline and oils mixed. Newly-treated nets are never 
carried inside the superstructure because of their volatility, 
which is dissipated after the first setting. 

Location of nets 

The depth at which the nets are set varies not only with 
the season and species but with the locality. The rather 
shallow waters are from 6 to 20 fm. (1 1 to 37 m.), and 
the deeper between 35 and SO fm. (64 to 91 m.). Nets 
are often set in the summer to as great a depth as 1 1 5 to 




Fig 50. Deck arrangement ofglllnetter with hauling equipment in the 
fore end of the vessel 



130 fm. (210 to 238 m.). Modern boats, with their 
lifting gear, have reduced the labour of deep-water 
fishing. Two men with a mechanical lifter can haul nets 
from over 30 fm. (55 m.), whereas it used to require 
from three to five men to do the same work by hand. 

Packing the nets 

The nets are stretched on a drying reel, and from^thig 
drying reel they are stowed in boxes with the leads 
arranged and stacked in tiers along the right-hand side 
of the box. The floats are then stowed in tiers throughout 
the remainder of the box. Great care is taken to ensure 
that each float corresponds to its lead, and to be certain 
that everything runs free when setting. The belly of the 
net is allowed to overhang the edge of the box, and when 
the reel is emptied that is, from 1,000 to 2,000 ft. 
(305 to 610 m.) the belling is folded over the float and 
leads. Hie ends of the float and lead lines hang from the 
box. When all the boxes are packed, they are loaded into 
the after or raised platform of the boat. The number of 



boxes to be set in any one day depends not only on 
locality but on the individual fisherman; from 10 to 
30 boxes is the usual number. Ideally, the width of the 
hull just forward of the setting platform will be that of a 
given number of boxes to prevent any movement due to 
rolling. If a vessel, is, say, 8 boxes in width and is to 





Fig. 51. Trough and roller equipment extending about 30 in. (76 cm.) 
over the side 



set 32 boxes, it will have two rows of 8 boxes each on 
the bottom and a second tier of two rows of 8 boxes. 
Net boxes are seldom stowed more than two high 
because of the weight and the inconvenience of handling 
and stowing them. 

Setting the nets 

When the fishing grounds are reached, a buoy anchor 
and buoy line are made ready. These are often carried 
on the housetop, but sometimes inside. The buoy and 
its anchor are then dropped with a suitable length of 
bridle which varies according to the depth of the water. 
When the buoy is in place and anchored, the vessel 






Fig, 52. Net hauler drums ranging from 10 to 30 in. (25 to 76 cm.) in 
diameter 



moves ahead at a speed of 3 to 5 knots, depending on the 
weather and the skill of the men setting the nets. Each 
man setting picks up a lead and a float from the box and 
throws them dear of the stern. When the box is almost 
empty, a third man, if there is one, moves box No. 2 into 
place and makes fast the ends so that its contents are 



FISHING METHODS AND DECK ARRANGEMENT GILLNET FISHING 



ready to be set when the first box 1$ empty. On a two- 
man boat, the last few leads and floats arc thrown by 
one man, the second man moving the next box into 
petition* Occasionally when a man and a, boy work the 
boat, the boy steers and moves the boxes into place, 
and the man throws the floats and leads. This can be 
dangerous as it is possible for the man to become en- 
tangled in the nets and be pulled overboard. When the 
desired length of net is in the water, a second bridle is 
made fast and attached to a second buoy and anchor. 

Hauling the nets 

The reverse process is used when hauling, but this is 
always done forward, as shown in fig. 50. The location 
of the forward opening varies from boat to boat. A 
trough and a roller, shown in fig. 51, extend over the 
side of the hull for approximately 30 in. (760 mm.). 
Large guides on the ends of the roller prevent the net 
from slipping off as it passes to a hauling drum via the 
trough. Drums, shown in fig. 52, range from about 
10 to 30 in. (254 to 760 mm.) in diameter, the last being 
the most common size. The hauler is so designed as to 
catch the leads, and the floats, being opposite the leads, 
are pulled evenly with them. The net, with the catch, 
sags between the float and the lead lines. Thus, as the nets 
pass the drum, the float and lead lines are, together with 
the fish, dispersed in the belly of the net. If the net is 
heavily loaded with fish, it is common, especially on two- 
man boats, to allow the fish to remain in the nets and to 
stow them in boxes; but with light catches the fish are 
picked from the nets as they come aboard. During 
hauling, the speed of the vessel is very slow and only 
sufficient power is maintained to ease the load on the 
hauler as much as possible. The filled boxes are stowed 
as directed by the skipper, while the wet nets are placed 
in another part of the vessel. In the winter the boat is 
kept as closed as possible because it is essential that the 
inside of the vessel remains warm, usually around 60F 
(16C), to prevent the nets freezing. 

After the haul is made, the vessel proceeds to the 
next set of nets to be hauled, and during this run some of 
the crew either pick the nets just hauled or, if they were 
picked during hauling, gut the fish. Hauling is normally 
done only after all the dry nets have been set. In port, 
the wet nets are wound on to drying reels, picked of 
debris, and stretched for drying, ready for repacking. 

The methods of handling the nets on mechanized boats 
differ little from those on unmechanized craft. The 
mechanical hauler of course, reduces labour. The con- 
tinuous superstructure was in general use long before 
the mechanical hauler. The modern hauler is very small, 
takes very little space, and can be adapted to any type of 
hull It is very efficient and needs but little maintenance. 
The drive is from the main engine through a shaft. The 
haulers are always operated from one side of the boat 
only, either port or starboard. 

Future development will be in the boats themselves, 
followed by improvements in fishing methods, 

Other methods have been tried for setting gillncts. One 



of these is the drum setter, similar to that used on the 
West Coast, but it has not be successful. 



The configuration of the superstructure varies according 
to the preference of the fisherman, builder or designer. 
The nets are always set from the stern, which can be open 
the entire width of the hull, and is the only universal 
feature in the superstructure. The large double doors on 
the sides of the superstructure aft are for loading and 
unloading the nets on the dock. The smaller boats all 
have a raised deck aft which is the steering flat and the 
net-setting flat and which is seldom less than 8 or 10 ft. 
(2.44 or 3.05 m.) in length fore and aft. All the boats, 
regardless of size, have double doors on the sides aft, 
and here, again, personal preference dictates their width 
and the manner in which they swing. Some open verti- 
cally, while others open horizontally. Advantages of 
horizontal hinging are that there is better control of the 
open area and it is reasonably watertight when running 
on a quartering sea or in rainy weather. The net-hauling 
doors are arranged over a great portion of the forward 
length. Generally, they are placed well forward to permit 
better control of the boat while hauling the nets, and the 
mechanical net haulers are usually located forward. A 
second door is often found in the hull, about half way 
between the forward and aft openings, used for picking 
when the net is to remain without resetting. 



Location of i 

It is very difficult to manoeuvre from the aft steering 
flat as visibility directly ahead is restricted at close 
quarters. So a hatch is often fitted in the cabin roof, 
permitting the helmsman to stand with at least his 
shoulders above the housetop. He steers with his feet 
on the wheel, the engine controls being within easy reach 
while in this position. A large window is fitted in the 
sides of the hull on some boats to give the helmsman 
better visibility, but he is still blind on the opposite 
side. There is often a large stack in the housetop for the 
exhaust pipe, which further restricts visibility. The larger 
boats of 55 ft. (16.8 m.) or more in length, usually have 
the pilot house amidships, with a separate steering flat 
above, and this gives very good visibility, especially as 
the engine exhaust is always aft. 

Height of saperstracture 

The headroom is usually about 7 ft. (2.1 m.) in the 
working flat, although there is no apparent reason for 
this excessive height The most efficient boats are those 
in which all openings are low to the water, or the working 
flat is raised to a point where it is convenient to lean out 
During hauling, especially with mechanical haulers, 
height is not as objectionable as it once was. Neverthe- 
less, height in the stern is still disliked because the nets 
have a tendency to fly off to leeward when being set. 
The superstructure across the stern, therefore, is usually 
carried just high enough along the bottom to allow it to 
be flush with the tops of the fish boxes. 



[67] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



The only fittings normally seen on superstructures are: 
a mooring bit forward, grab rails just forward of the 
break into the pilot house, running lights atop the pilot 
house with a horn, and grab rails on the raised deck aft. 




Fig. 53. Gittnetter, Boat A, where the entire bottom is developed on a 
series of cones 



The minimum equipment required by law, such as fire 
extinguishers, etc. is all that is carried. For the most part, 
gillnetters have no accommodation for the fishermen. 

Maia 

Although there are no fixed types of boats for gillnetting, 
the main specifications of some Great Lakes gillnetters 
are given in table 1. 

Fig. 53. This is the lines plan of Boat A in table 1, 
which is also shown in fig. 47. In this vessel the entire 
bottom was developed on a series of cones, with the 
primary apex just forward of station O and in line 




Fig. 54. Gtibetter, Boat B, being a design study and modified version 
of the previous figure, with a reduced height of superstructure 



with the fairbody extended from stations 2 and 3. The 
superstructure heights are normal for the average gill- 
netter as are the locations of the openings. The working 
flat is above the design waterline and, considering the 
team, results in a very spacious platform. This is a 
standard hull design and built by the Rargard Company 
of Marinette, Wisconsin. 



Fig. 54 is a design study and modified version of the 
vessel shown in fig. 53, namely Boat B in table I. Here 
there is a drastic reduction in superstructure height, which 
is not only weight-saving, but also permits a reduction of 
ballast as well as displacement. Development on this 
hull is conical in the forward sections (0 to 3) breaking 
into cylindrical at stations 3 to 5, and the afterbody 
sections are then straight lines between the fairbody and 
the chines, It is normal on gillnetters to have as much 
outside keel or deadwood as is shown. This could be 
drastically reduced and is, for the most part, a carry-over 
from the wooden hulls. Although reduction in wetted 
surface would be small, improvement in manoeuvrability 
would be great and well worth the reduction. This vessel 
has not been built. 

Fig. 55. More and more men, having steady employ- 
ment ashore, fish only part time and that mostly only 
during the spring, summer and fall, and fishing is limited 
to perch and some chub. Boat C in table 1 was designed 




Fig. 55, Gilinetter, Boat C, constructed of aluminium alloy and 
designed for high speed, with accommodation for two 

by the author originally for this purpose. The pilot hull, 
however, was converted to a handliner and is to fish as a 
gillnetter in the North during the summer, and as a 
handliner along the Gulf Coast during the winter. 
Constructed of aluminium alloy and welded throughout, 
it was designed for high speeds in rough water and to do 
some ice breaking. Her light weight, however, will not 
permit operation in thick ice. The beam was limited 
to 8 ft (2.44 m.) so the boat could be carried on a trailer. 
There is limited accommodation for two, and the engine 
is aft, operating through a V-drivc unit. 

Several vessels, in the near future, will be built from 
the same general plan but the hulls will be of steel. The 
complete boat will not cost more than about 94,000 
(1,430). If the vessel is to be operated from one port 
only, cabin accommodation will be omitted, a self- 
draining cockpit fitted in lieu of the foredeck, a bow 
roller installed, and the cabin used to stow nets and fish, 
during the haul, which will be moved to adjust trim while 
preparing for the next haul. 



FISHING METHODS AND DECK ARRANGEMENT OltLWBT FISHING 

Fig. 56 is the Boat D in table L This is the result of a 
preliminary investigation of a high-speed gillnetter. 
This vessel has the ability to break ice up to, say, 6 in. 
(15 cm.) in thickness. The short superstructure reduces 











TABLE 2 




Sectional 


*<*** 


ittoo fa **** 


ff* 


Station 


Boca A 


BoatB 


BoatC 





-- 


_^ . 


0.0084 


i 


0.1600 


0.1421 


0.2000 


1 


0.3300 


0.2970 


0.3891 


2 


0<6500 


0.5787 


0.6695 


3 


0.8575 


0.8122 


0.8410 


4 


0.9700 


0.9543 


0.9456 


5 


1.0000 


1.0000 


0.9874 


6 


0.9750 


0.9442 


1.0000 


7 


0.8750 


0.8046 


0.9707 


8 


0.7000 


0.6015 


0.9247 


9 


0.4400 


0.3604 


0.8787 


10 


0.1250 


0.1015 


0.8201 



Fig. 56. Gillnetter, Boat D, being the result of a preliminary investiga- 
tion for a high-speed craft 

the weight considerably, and is still of sufficient length 
to warrant the hauling of nets from inside. Setting would 
be from the stern, and during bad weather a lifeboat 
spray hood could be erected to advantage. The stowage 



BoatD 



0.1444 
0,3000 
0.5555 
0.7667 
05222 
1.0000 
0.9889 
0.9444 
0.8778 
0,8028 
0.7222 



of nets, whether for setting or after they are hauled, 
would be below decks on a fore and aft roller conveyor 
that passes port and starboard of the engine. This boat 
would cost between 82,500 and $3,500 (890 to 1,250), 
not including engine and equipment. 

Table 2 shows the sectional area of these four vessels,, 
and table 3 their power requirements. 



Construction 

TABLE l With the depletion of good shipbuilding timber and a 
Principal particulars of hulls of Great Lake gUlnetters constant increase in costs, coupled with the ever-declin- 
ing number of skilled shipwrights, the introduction of 
Boat A Boat B BoatC Boat D ^ gtcd ^1^^ was inevitable. The early steel hulls 

Length overall, LOA . ft. 40.42 40.17 26.33 36.0 followed very closely the shape of the wooden hull that 
T . . .. _ ?. 12.32 12.24 8.03 10.97 i s t h e tugboat hull. It was soon found that these hulk 
Ungthmwaterhne,L ft. 38.87 38.67 23.59 33.0^ wer e, in many ises, at least as heavy if not heavier th^ 

Length between perpen- their wooden counterparts. The use of the long super- 
dicular, LBP , . ft. 39.0 39.0 23.25 33.0 
m. 11.89 11.89 7.09 10.06 


Breadth, mid. at sheer, B 
Breadth, mid. at chine . 
Draught, T . 


ft. 
m. 
ft. 
m. 
ft. 
m. 


12.30 

3.81 
10.83 
3.30 
3.92 
1.19 


12.30 

3.81 
10.83 
3.30 
3.92 
1.19 


v.yo 
2.43 
6.67 
2.03 
2.25 
0.69 


1U.U 
3.05 
8.50 
2.59 
2.50 
0.76 


Horsepower, o 


TABLE 3 
oefflcknts mti itinpltTfn" >ti H- l ** i g rt> ratio 


Displacement, A, . 

A . 


tons 
ton 


11.98 
12.17 


11.02 
11.20 


2.50 
2.54 


4.99 
5.07 




Boat A 


BoatB 


BoatC 


Boat D 


LCB from FP in % of 
LBP . 
Water plane area, A w . 


sq.ft. 
sq. m. 


0.514 
356 
33.07 


0.508 
354 
32.89 


0.560 
127 
11.80 


0.567 
225 
20.90 


Designed speed 
(trial condition) 
h.p. . 


11 
150 


11.5 
150 


22 
105 


20 
150 


Tons per in. . 
., ,. cm. 




0.824 
0.329 


0.819 
0.328 


0.294 
0.117 


0.522 
0.208 


Type of engine 


Diesel 


Diesel 


Petrol Petrol/Diesel 


LCF from FP in % of 






















LBP 




A 4*4 


557 


579 


0.582 




202 


186 


199 


139 


LrfDa ... 

Displacement per in. (cm.) 
trim by stern . 


Ib. 


\J,JJJ 

102 


\t,jj t 
104 


U.J 1 7 

53 


96 


(LBP/100)' * 

LBP/A 1 /* . 


5.21 


5.36 


5,24 


5.90 




kg. 


18.40 


18.60 


9.48 


17.15 


v 










Wetted surface, S ' 


sq.ft. 


35 
487 


39 

477 


27 
168 


22*' 
281 


V 


1.76 

* 


1.84 


4.56 


3.4S 


D~~ai_ 


sq. m. 
sq. ft 


45.24 
291 


44.31 
245 


15.61 
101 


26.10 
153 


V 


0.524 


0.548 


1.36 


1.04 


Profile above water, A 


BMt . 


sq. m. 
ft. 


27.03 
6.93 


22.76 
7.26 


9.38 
4.43 


14.21 
6.37 


<p $ . 


0.6923 


0.6454 


0.8435 


0.7881 


BMi . 


m. 
ft. 


2.11 
81.28 


2.21 
87.48 


1.35 
49.21 


1.94 
84.71 


$ ... 


0.4090 


0.4032 


0.5500 


0.4938 


Moment to change trim/ 


m. 


24.77 


26.66 


15.00 


25.82 


P 


0.5908 


0.6247 


0.6521 


0.6266 


in. (cm.) . 


ft.tons 
m.tofi 


2.08 
0.254 


2.06 
0.251 


0.45 
0.055 


1.07 
0.131 


a 


0.8428 


0.8372 


0.8170 


0,7902 


lJ 



FISHING BOATS OF THE WORLD : 2 TACTICS 



TAKE 4 

for to I 



BomtsAcmdB 



Keel plate . 
Stem bar 

Longitudinal spacing 
Chine bar . 

Gunwhatobar 
Frames 
Frame spacing 

Bottom shell 
Side shell . 
Working flat 
Superstructure 
Superstructure, deck 
Superstructure, deck beams 
Main deck beams 



in. 
on. 

in. 



in. 



in. 
on. 

in. 
mm. 

in. 
mm* 

in. 



in. 



in. 
cm, 

in. 
cm. 

in. 
cm. 

in. 



in. 
mm. 

in. 
mm. 

in. 



in. 
mm. 

in. 

mm. 

in. 
mm. 



*x5 
19 



x127 



.i 



round bar 



2 
51 



6.35 X63.5 
15 forward JL 

19 midship JL 
4o.3 

24aflJL 
61 



*4.8 

Iix6ftr 
38x152 



BoatC 



Boat D 



Ix3x 

32x76x4:8 



1x4 
19 



UxA fla 
32x4:8 



x102 
flat bar 



9 
22.9 

J round bar aft 

12.7 

i plate forward 
6.35 



I|x2fxiangle 
32x63.5x6.35 

14 forward }L 

28 elsewhere 

71 



Jx3fir 
22x76 



t plywood 
9.5 

1 x If laminated spruce and fir 
25.4x41.3 

2ixl*xi angle 
63.5x32x6.35 



fx4 bulb plate 
15.9x102,, 



flat bar 



11 
28 

| round bar aft 

15.9 

flat bar forward 
4.8 

s!* 



48x63.5 

15 forward JL 

38 
30 elsewhere 

76 



!, 



Jx3fir 
22x76 



(plywood 
9.5 

1 x 21 laminated white oak 
25.4x63.5 



3.2x63.5 



Note. Boats A. B and D are mild steel; Boat C is aluminium alloy 6061T-6, with a nominal chemical composition of 1 % magnesium, 
0.6% silicon, 0.25% chromium, and 0.25% copper. 



structure in steel construction again caused a stability 
problem, since it was not possible to build as light a 
structure which could be walked on without extensive 
framing. This, in turn, increased the cost out of all 
proportion. To counteract the effects of the increased 
weight and the raising of the centre of gravity, the vessels 
were heavily ballasted* Someof the newer hulls began to 
increase beam to offset the superstructure weight and 
ballast. For a number of years this was the major im- 
provement; but as the propulsion plants became lighter, 



the hulls became wider, again the V-bottom was intro- 
duced to farther reduce the initial cost This came only 
after welding was in general use. The riveting of a V- 
bottoni hull has never been economical. 

Most new gillnetters are of steel. The steel hull is 
easier to maintain, does not leak, and can be worked 
through the ice fields with little or no danger of punctur- 
ing or opening up. The Great Lakes, on the whole, are 
surrounded by metal working plants; therefore, metal- 
working skin is common* Numerous small plants have 



170] 



FISHING METHODS AND DECK ARRANGEMENT GILLNET FISHING 



the necessary equipment a* well as a plentiful supply of 
skilled metal workers so that they can economically build 
boats either as a full-time or part-time business. 

The use of aluminium alloys for gtlhietter construction 
on the Lakes is not warranted at the present time: it is 
too costly and the corrosion rate of fresh water steel 
vessels is very small. Lighter weight, by itself, is of no 
importance, in fact the greater weight of a steel gillncttcr 
is an advantage in winter when it is used as an ice breaker. 

There has been an increasing tendency to copy the 
yacht hull form up to the sheer line in both round and 
V-bottom hulls. While it is true that plate development 
does reduce the cost of labour in plating, the extreme to 
which it is occasionally carried increases the cost of fram- 
ing and requires more horsepower than is installed to 
achieve the maximum hull efficiency. Unless the desired 
speed is in excess of IS knots, there is very little to be 
gained in carrying the plate development all the way to 
the transom. 

Table 4 gives the scantlings for both steel and aluminium 
gillncttcr hulls. 

Engines 

With the increasing cost of fuel, the most popular engine 
is still the diesel, even for smaller boats. The air-cooled 
diesel promises to become popular in the smaller perch 
boats. It is felt by the author that the most economical 
engine will be between 5 and 25 h.p. 

Engine power varies widely in gillnetters. In the past, 
engines of low power were common, but due to their 
lighter weight and lower cost per h.p., the higher powered 
engines are preferable today. An increase in horsepower 
makes it desirable to have a hull capable of higher speeds. 
Unfortunately, higher speeds require a flatter and wider 
transom which, in turn, necessitates a fuller bow to 
prevent running under. The excessive beam necessary 
because of the vast amount of superstructure causes the 
half angle of entrance to become very full if any of the 
developed plating methods are used. 

Problems affecting the industry 

Perhaps the greatest menace to fishing on the Great 
Lakes has been the lamprey eel. During the war years, 
the lamprey spread through Lake Huron and throughout 
the entire length of Lake Michigan. The average annual 
catch of trout between 1812 and 194S was over 2,500 tons, 
whereas today there are none in Lakes Michigan, Huron 
and Erie. Unfortunately, the fight to control the lamprey 
eel came only after it had destroyed the trout in Lakes 
Michigan and Huron and had begun to spread into Lake 
Superior. 

The lower Lakes fishermen now concentrate on perch, 
chub, smelt, whitefish, herring, suckers, some carp, etc., 
but die catch does not meet the demand. Trout are still 
caught in Lake Superior, but they are small and of a 
recent stock. The only solution is the eradication of the 
lamprey, or at least its control, and the restocking of 
trout throughout the Lakes. 

Poaching in the Great Lakes is quite common, and 
although there are laws against it they are very lenient 



and the fines so small that the commercial fisherman 
has little protection against poachers. 

The Lakes fishermen are somewhat concerned that the 
opening of the St. Lawrence Seaway may encourage 
migrations of certain species of trash fish which will not 
improve the Great Lakes fishing. 

Some other problems are: (1) pollution of water by 
industrial plants; (2) restocking the Lakes with trout and 
other compatible species; (3) the expected population 
increase which will utilize the Lakes to their fullest; and 
(4) educating the population of the Lakes States to eat 
more fresh-water fish, rather than to import salt-water 
fish. 

Unless these problems are solved, gillnet fishing could 
ultimately be destroyed. When the catches amounted 
to upwards of a ton per day, the large gillnetter with great 
beam was a necessity. Today, however, the average catch 
is more in the range of 400 or 500 Ib. (180 or 230 kg.) or 
even less per day, so that large boats are not economical 
to own and operate. It would be possible in a period of, 
say, 20 years to stock the Lakes with trout and many other 
species of food fish, thus strengthening the fishing industry 
which, in turn, would then warrant extensive research and 
development of not only hull design and performance,, 
but of fishing methods themselves. 

Future developments 

There are two possibilities for future development in 
Great Lakes fishing vessels. One is the one-man perch 
boat, with a hull of between 18 and 25 ft (5.5 and 7.6 m.), 
all open or at most with a small cuddy or wind break. 
The cost would be small, and the nets would be limited to 
three or four boxes. The other possibility is the introduc- 
tion of the trawler, which would be not more than 
36 to 45 ft. (1 1 to 14 m.) and would be operated by two 
or three men. It would be used primarily to catch trash 
fish for fertilizer or mink feeding, and would sort out 
marketable species if market conditions warranted. 

Just recently there have been some developments in the 
field of welding thin material 0.015 to 0.125 in. (0.381 
to 3.17 mm.) at high production speeds, using the 
inert-gas-consumable electrode. This development will 
be a boon to designers as well as to builders, as the rule 
of thumb has always dictated that the minimum economi- 
cal thickness of welded material is 0.125 in. (3.17 mm.) 
or greater. To weld thinner material than this, highly 
skilled men were required and, even then, there was 
excessive burn-through and distortion due to the slow 
welding speeds necessitated by the thin plate. The use of 
thinner material will allow large reductions in super- 
structure weight, thereby permitting many refinements in 
hull design. This lighter material will also be feasible in 
the construction of very small perch boats which would 
have been too heavy if constructed of 0.125 in. 
(3.17 mm.) steel. Heretofore, builders have been reluc- 
tant to attempt the smaller and lighter steel hulls and, 
when forced to build them, increased the weight of die 
materials to a point where the performance was unsatis- 
factory, or they increased the cost of construction to 



[71] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



uch a degree that it was no longer economical to use 
stccL 

In the future, the building of small perch boats will 
also encourage the revival of the wooden hull. Many of 
the boats will no doubt be built by the fishermen them- 
selves to save money. While some are skilled in boat- 
building, the majority arc not; therefore, the hull design 
and construction will have to be kept simple. There is 
every possibility that the cross-planked hull of the 
Chesapeake Bay could be reintroduced to the Lakes. 
The system was never popular on the Lakes, which was 



mainly due to not understanding the method of con- 
struction and to the attempt to lighten backbone and 
bottom planking. This method of planking a hull could 
result in some very practical hull designs that would be 
easy to build and would not require a great deal of 
knowledge as far as lofting or carpentry is concerned. 
By the elimination of bottom framing, it would be more 
economical to build than a longitudinally planked 
V-bottom hull, and the increased weight by cross plank- 
ing would be beneficial rather than detrimental to the 
development of the perch boats. 



172] 



LONGLINE FISHING: DECK DESIGN AND EQUIPMENT 

by 
YOSHIAKI KANASASHI 



Characteristic* of tuna longliners are large fish rooms and fuel oil capacity. Electric welding, light alloys and new insulating material! 
have reduced ships* weights considerably, and engine room arrangements have been improved. 

Accurate navigation instruments are used to ensure safe voyages and economic operation. Excellent insulation materials and 
refrigeration equipment are used to preserve the freshness of the catch. 

As fishing operations are carried out in tropical waters, improvements in the living quarters are constantly sought. Overseas bases 
have recently been established for vessels fishing far-distant grounds. 



EQUIPEMENT DE PONT POUR LA PECHE AUX PALANGRES 

Les thoniers-palangriers sont caract&isfe par un grand espace itservd i la <le et une grande (apacit6 pour k Carburant. Lasoudure 
electrique, les aliiagcs legere et les materiaux isolants ont consid&ablement reduit le poids des navires, ct les dispositions de la salle det 
machines ont 6tt ameliories. 

Pour assurer des voyages sftrs et un fonctionnement economique, on utilise des instruments de navigation precis. Pour preserver 
la fraicheur de la peche on utilise d'excellents materiaux isolants et des installations frigorifiques et de conditionnement de Fair. 

Comme les operations de peche ont lieu dans des men tropicales, on recherche constammont des ameliorations a apporter aux 
emmtaagements pour le logement. Recemment, on a 6tabli des bases outrc-mer pour les navires ptehant sur des lieux tres Ooignes. 



LA PESCA CON PALANGRES: EQUIPO Y FORMA DE LA CUBIERTA 

Los atuneros se caracterizan por la gran capacidad de sus bodegas y de sus tanques de combustible. La soldadura ettctrica, las 
ateaciones Jigeras, y los materiales aislantes ban reducido considerablemente el peso de los barcos y se ha mejorado la distributi6n de la 
maquinaria en la sala de maquinas. 

Se emplean instmmentos de navegacion de precisi6n para asegurar que los viajes se haran sin novedad y que el fundonamiento 
sera econ6mico. Se emplean excelcntes materiales aislantes, equipo de refrigeraci6n y de aoondicionainiento de aire para mantener las 
frescura de la pesca. 

Como la pesca se realiza en aguas tdrridas, se trata constantemente de mejorar los alojamientos. Ultimamente se ban estableckk? 
bases lejos del Japon para los barcos que pescan en caladeros muy distantes. 



JAPANESE tuna fishing has moved from coastal 
waters to the deep sea, the size of the ships has 
increased, and the equipment has been much im- 
proved, although more improvement is still desirable. 

The largest tuna longlincr in 1941 was ISO GT, with a 
maximum cruising range of 5,000 sea miles, but the ships 
today range up to 1,900 GT, capable of voyages of 
23,000 sea miles. 

Tuna are caught mainly by two types of vessel, namely, 
longliners and combination boats. Longliners are built 
of wood or steel, most boats of 100 to 1,900 GT being of 
steel. Combination boats are suitable for both longline 
and pole-line fishing; the pole-line season for tuna being 
short, this type of boat is limited to 300 GT. 

There are three types of operation: single boat, group, 
and from a base abroad. Mostly it is single boat, but 
group operation 'was started about 1950 'on distant 
grounds, using a mothership to service the catcher boats. 

For the third type of fishing, there are shore bases near 
the fishing grounds. 

A longline fishing trip lasts three to four months, so 
the boats must be very seaworthy, of good stability, and 



provide comfortable accommodation for the crew. And, 
of course, keeping the catch fresh is of prime importance. 

FISHING GEAR 

Longlining is the best method for catching tuna at a 
depth of 260 to 525 ft. (80 to 160 m.). Large catches can 
be made at low cost, and it can be carried out on any 
scale, according to the capital invested. 

Layout and construction of the fishing gear is shown in 
fig. 57, 58, and 59. The principal items are main fines 
(cotton or nylon yarn), branch lines (cotton or nylon 
yarn) and hooks. Auxiliary tools are buoy lines, buoys 
(glass balls), bamboo rods and lamp buoys. A set of unit 
line is 650 to l,30p ft. (200 to 400 m.) long, with branch 
lines about 100 ft (30 m.) long, all coiled and stacked 
in a basket when not in use. The number of branch tines 
per unit line varies according to the species of fiih to be 
caught: 5 to 6 for bluefin tuna, and 12 to 13 for albacore. 
A longline consists of 350 to 400 sets of unit fines, giving 
the main fine an overall length of 50 to 75 mites (80 to 
120km.). The depth of hooks is adjusted by the booy 
fine to meet the swimming shoals, and is about 35 to 



[73] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



120 ft. (11 to 37 m.) for bhtefin tuna and 180 ft. (55 m.) 
for albacore. Some fishermen now UK radio buoys to 
prevent tontine* from being snapped or carried away. 




Fig. 57. Longllne layout 

Before departure the owners of longliners collect as much 
data as possible concerning the fishing grounds, mainly 
by radio from other boats at sea, and the longliner master 
is given an approximate target area. The boats as they 
approach the area indicated begin to measure the sea 
water temperature, because tuna live in definite tempera- 
tures, and in particular near the current rip where warm 
and cold currents meet and plankton are produced. 
Every morning at dawn the unit lines are joined with metal 
couplings, the hooks are baited with frozen sauries, and 
the sets are cast into the sea from the stern at 8 to 9 a.m., 
the speed of the boat being about 8 knots. The line is 



LdmaBuov 




JML 
Fig. 58. Longltne construction 

cast at a rate of about 100 sets of unit lines an hour. The 
boat drifts until about 1 1 a.m., when it comes around to 
the end of the line which was first thrown out and starts 
to haul with the line hauter. The fish come up through an 
opening in the bulwark to the deck, where they are gutted, 
washed and prepared for freezing or ice storage. 



The longlines are then carried by a conveyor to the 
port side and stowed in a housing on die poop deck, and 
the day's work is finished. 




Fig. 59. Lamp buoy 

GENERAL ARRANGEMENT 

Larger boats are not necessarily more profitable but, 
because catches have declined in the pre-war fishing 
areas, larger boats have been built to increase the cruising 
range and they have been provided with more refrigera- 
ting capacity. 




Fit. 60. LoHflir* fitkixg boat 

To economize in the time spent sailing to and from the 
grounds, and to keep the catch fresh, a inothership 
system has been introduced. Fig. 60 is a sketch of a 
fishing boat, and the general layouts of 250 and 1 ,000 GT 
boats are shown in fig. 61 and 62. The 250 GT vessel 



[74] 



FISHING METHODS AND DECK ARRANGEMENT LONGLINE FISHING 




BO ft 



e 4 



Fig. 61. General arrangement of 250 GT tuna longtiner 



has a waterline length of 122.S ft. (37.34 m.), breadth of 
22.31 ft. (6.8 m.) and depth of 10.99 ft. (3.35 m.) and is 
powered by a 550 h.p. engine. The 1,000 GT vessel has a 
waterline length of 196.6 ft. (59.9 m.), breadth of 36.1 ft. 
(11 m.) and depth of 17.39 ft. (5.30 m.) and is powered 
by a 1,500 h.p. engine. 

Holds 

Holds are divided into 3 to 5 compartments. In a boat 
with small refrigerating capacity, such as the combination 



craft, the hold is divided into 6 to 12 small compartments 
for crushed ice storage, and a large compartment for fish 
storage, each cubic foot of which can hold about 
34.3 Ib. of tuna fish (0.55 ton/cu. m.). In flush-deck 
boats, the hold is sometimes located aft of the engine 
room. Two longitudinal partition boards and one or two 
shelves are inserted into each fish hold. A bilge well and 
suction pipe are fitted in each hold, the bilge being emptied 
by a pump in the engine room, or by a hand pump on the 
deck. The ice needed is 0.5 tons per ton of fish to be 




Ftf.62. 



[75] 



FISHING BOATS OF Tl 

cooled. The bah i saury and squid. Details of freezing 
arc given in the paper "Tuna freezing" on 



Friction multi-plate fine haulers are most widely used, 
but tome fishermen prefer the hydraulic coupling type. 
Two sets of line haulers are placed in tandem forward 
on the starboard side, with motors aft of the forecastle. 
There are side rollers on the bulwarks so that the hooked 




Fig. 63. Schematic towing arrangement for a catcher boat on a 
mothersMp often than 1,000 GT 



fish can be pulled up to the deck. Lines are stored on the 
boat deck or aft of the poop deck. The gear is carried by 
conveyor belt to its storage place aft. Memberships store 
equipment used in the catcher boats (Yagi, 1955). 




Fig. 64. Lifting arrangement for a catcher boat on a mother -ship 
of more than 1,000 GT 



Foremast booms and detachable davits sat used for 
loading and unloading on both longliners and combina- 
tion boats. Another method is to run three strands of 
wire, with triangular rings, from the foremast through 
hatchways, and to use a block and tackle at the warping 
nd of the windlass. 



WORLD 


: 2 TACTICS 






TABLE 


5 


NuAter 


0i cvews luff 






Longliners 


Combit 


Gross tons Crew 
GT 


Gross tons 
GT 


250 
350 
700 
1,000 
1,500 


30 
34 to 37 
45 to 47 
65 to 80 
90 


150 
180 
220 
300 



Crew 



50 
55 

60 
70 



One or two sets of derrick posts are erected on deck, 
the loads being hauled by winches with drum-wound 
ropes. 

Conveyors are used to carry both gear and catch. 

Accommodation 

Large crews are carried, especially on combination boats, 
and accommodation is inadequate, but designers are 
paying more attention to this problem. Table 5 gives the 
number of crew for various sizes of boats. 

Air conditioning is desirable for men working in 
tropical waters, but not many boats are so equipped. 
Mechanical ventilation is common on large longliners, 
(ceiling heights are limited to 6.2 to 6.9 ft. or 1 .9 to 2. 1 m. 
to lower the centre of gravity) and air conditioning and 
other facilities are beginning to be installed on many 
smaller boats. 

Boats for single operation 

These are mostly in the 250 to 350 GT class and appear 
to be most economical and efficient for the time being. 
Ships under 300 GT are all of the flush-deck type, while 
those over 350 GT often have a long poop deck. Every 
boat has a freezing chamber located forward of the deck 



TABLE 6 
Principal partiadm of wood an 



Length, L 

^% ___ .*..<- < 
JBratatn, a . 

Depth, D 

Gross tonnage, OT 
Main engine . 
Air compressor 
Generator 
Line hauler . 
Wireless equipment 

Speed, light, at 110% 
engine -load, knots, 

Speed, loaded, at 
engine load, 

^~ * 



Aluminium 

46.5ft. (14.20m.)- 
11.8ft. (3.60m.) 
5.25ft. (1.60m.) 
19.80 



3 h.p. hot bulb 

3kW 

Small type 

10 W short wave 

wireless phone 



9.08 



Wood 

52.5ft. (16.00m.) 

12.1ft. (3.70m.) 

5.4ft. (1.65m.) 

19.50 

90h.p. diesel 
3 h.p. hot bulb 

3kW 
Small type 
10 W short wave 
wireless phone 



9.42 



Lightweight, ton 
Fish hold capacity 



7.40 8JQ1 

16.40 16.10 

530 cu. ft (15.0cu.m.) 360 cu. ft. (10.3 own.) 



176] 



FISHING METHODS AND DECK ARRANGEMENT LONOLINE FISHING 



house or the poop, bat the refrigerating capacity of the 
flush-deck type is kept below 4 tons per day because of 
the limited space. 

MothersWp opcratkm 

Boats smaller than 1,000 GT have no deck space to carry 
a catcher boat, but it is towed as shown in fig. 63. Derrick 
post booms and a winch are installed aft, and the stern is 
strengthened. Boats larger than 1,000 GT carry one or 
more catcher boats on each side of the deck as shown in 
fig. 64. This type of boat has two rigid derrick booms and 
four units of 3 to 5 ton winches, so that catcher boats are 
hauled with drum-wound ropes, the deck being rein- 
forced and provided with rigid rope-winding equipment. 
All motherships have long poops and engines aft, with 
a freezing room forward of the poop. Crew accommoda- 
tion is aft of the poop and the deckhouse. 



arrangement plan of a 216 GT combination boat is 
shown in fig, 65, having the below principal particulars: 

L =108.3 ft. (33m.) 
B =2L65ft. (6.6m.) 
D=ll ft. (3.35m.) 
Engine 650 h.p. 

The hold space of longliners is 20 to 40 per cent, 
larger, as it is not divided into small compartments. 

Half the number of crew is needed, and living quarters 
can be provided on the upper deck. 

Some 30 to 40 per cent, more fuel can be carried, which 
extends the cruising range. 

Larger boats of this type can be built so that freezing 
equipment can be installed and longer voyages made. 

Table 7 compares boats of nearly equal dimensions. 




t t i 




o 10 y 

* ill * Am. 

Fig. 65. General arrangement of a combination tuna longliner and skipjack pole and line fishing boat 



Catcher boats must be seaworthy. To ensure easy 
operation without sacrificing stability, many difficult 
problems confront naval architects: the rolling period 
should be long; the speed should be more than 8 knots at 
full load condition, and it should be possible to handle 
200 to 250 sets of lines. The weight of catchers should 
also be reduced. At present, they are built of wood or 
light alloy, but study of this problem may lead to lighter 
boats. Table 6 compares the wood and light alloy types. 



._ i ud combination boats 

These boats have different functions and it is difficult to 
compare their merits and disadvantages. The general 



MAIN SPECIFICATIONS AND CONSTRUCTION 

The Japanese Government issues fishing licences for 

certain fixed GT, so that shipowners tend to build the 

largest ships possible within the GT allocated to them, 

based on maximum loading capacity, cruising range and 

speed. 

Relations between grow t<*m*ge (Gl), critic orator (CN) 

and feagth (LBP) 

The relations between GT-CN and GT-LBP are shown 
in fig. 66 and 67 respectively. The relation between 
GT-CN can be expressed by the folio wing equations: 

Longiiner, poop-deck type 
GT=(0.00906 to 0.00920) xCN(cu. ft) 
(OJ2 to <U23)xCN (cu. m,) 



[77] 



FISHING BOATS OF THE WORLD : 2 TACTiCS 



TABLE 7 


Type 


LongUmer 


Combination 
boat 


Gross tonnage, GT 


309.54 


239.24 


299.00 


215.59 


Year built 


1958 


1958 


1955 


1958 


Length, LBP . . ft. 
m. 


110 
40.00 


115 
35.00 


124 
37.80 


109 
33.20 


Breadth, mid., B . .ft. 
m. 


24.6 
7.50 


22.3 
6.80 


23.6 
7.20 


21.6 
6.60 


Depth, mid., D . .ft. 
m. 


12 
3,70 


11 
3.35 


11.8 
3.60 


11 

3.35 


GT/LBPxBxD . 


0.278 


0.300 


0.305 


0.290 


Capacity: 
Fish hold (a) . cu. ft. 11,050 
cu. m. 313 
Fuel oil tank (b) cu. ft. 5,890 
cu. m. 167 
Freshwater tank (c) cu. ft. 91 1 
cu. m. 25.8 
cu.ft./GT57.9 
cu.m./GT 1.64 


7,800 
221 
4,250 
120 
530 
15 
52.6 
1.49 


7,560 
214 
4,010 
113.5 
985 
27.9 
42.0 
1.19 


5,400 
153 
3,200 
91 
826 
23.4 
43.8 
1.24 


Main engine, h.p. 


650 


500 


650 


650 


Refrigerating machinery 
Japanese RT 
kcal. 


58.5 
177,000 


30 
91,000 


14.0 
42,000 


13.5 
41,000 


Freezing capacity . ton/day 


6.5 


1.9 








Cruising range 
nautical mites 


19,800 


14,920 


11,950 


9,120 


Navigation days . 


75 


71 


51 


41 


Weight of catch, ton . 


170 


116 


105 


69 


Weight of catch/GT . 


0.55 


0.48 


0.35 


0.32 


Cruising speed in knots, V 


11.01 


10.32 


10.71 


10.23 


Max. trial speed, in knots, V. 


12.09 


11.39 


11.68 


11.27 


Crew: deck 
engine 
32k . 


21 
8 
2 


16 
1) 

1 


64 
10 

2 


45 
8 

2 ' 


Total 


31 


28 


76 


55 



Longliner, flush-deck type 
GT=0.00850xCN (cu. ft.) 
=0.30xCN(cu. m.) 

Combination boat 
GT=*0.00734xCN (cu. ft.) 
-0.295 xCN(cu. m.) 



The relation between GT and LBP can be expressed by 
Hie following equations: 

Longliner, poop-deck type 
300 to 600 GT 

LBP (ft.)=(18.37 to 19.03) x-^GT 
(m.)=(5.60to 5.80) x^GT 
600 to 2,000 GT 

LBP (ft.)=(19.36 to 19.52) x-^GT 
(m.)= (5.90 to 5.95)x^GT 

Longliner, flush-deck type 
Below 600 GT 

LBP (ft.)=(19.03 to 19.52) x-^GT 
(m.)= (5.80 to 5. 



Combination boat 
Below 300 GT 

LBP (ft.)=(17.39 to 18.37) 
(m.)= (5.30 to 5.60) 




UftfaO 



Fig. 66. Relation between gross tonnage and cubic number for 
longliners and combination boats 



Relations between depth (D), bean (B), draught (T) and 
LBP 

For motherships, carrying one or more catcher boats, 
allowance must also be made for catchers and the 
stability when lifting them. The location of freezing 
rooms must, also be considered. With the recent trend 
towards increasing the weight of fittings, the value of KG 
has been gradually enlarged, making the breadth corre- 
spondingly larger. 

Fig. 68 shows the values of beam (B) and depth (D) 
against LBP, which can be expressed by the following 
equations: 

LBP 164 ft. (50 m.) (about 600 GT) 
B (ft.)-0.11 LBP+(10.17 to 9.51) 
(m.)=0.11 LBP+ (3.1 to 2.9) 
LBP>J64ft. (50m.) 

B (ft.)-0.20 LBP-3.61 
(m.)-0.20 LBP-1.10 



[78] 



FISHING METHODS AND DECK ARRANGEMENT LONGLINE FISHING 




Fig. 67. Relation between gross tonnage and length for longliners 
and combination boats 



Fig. 69. Relation between light weight and cubic number for long- 
liners ana combination boats 



Weights and longitudinal c*otre of gravity (LCG) 

Light weights are shown against CN, in fig. 69, and hull 
weights in fig. 70. 



LBP<il64ft. (50m.) 

D (ft.)=0.068 LBP-K3.61 to 2.95) 
(m.)=0.068LBP+(l.l to 0.90) 

LBP>164ft. (50m.) 

D (ft.)=0.080 LBP+(1.64 to 1.31) 
(m.)=0.080 LBP+(0.50 to 0.40) 

Values of B/D range between 1.95 and 2.30, usually 
between 2.0 and 2.1. In the standard design, draught is 
equal to 85 per cent, of depth, the block coefficients being 
about 0.66 to 0.70. 



* * 




jtL 



r 



UMQ Nftritap ** 




tfrif 



Tlrn 



Fig. 68. *** 



,600 cu. ft. (1,800 cu. m.) (about 600 GT) 
Light weight (ton)=(0.0102 to 0.0093) x CN (cu. ft) 
=(0.36 to 0.33) XCN (cu. m.) 

CN>63,600 cu. ft. (1,800 cu. m.) 
Light weight (ton)=(0.0093 to 0.0076) xCN (cu. ft.) 
=(0.33 to 0.27) xCN (cu. m.) 



3,600 cu. ft. (1,800 cu. m.) 
Steel hull weight=(0.0051 to 0.0038) xCN (cu. ft.) 
=(0.18 to 0.135) xCN (cu. m.) 

CN>63,600 cu. ft. (1,800 cu. m.) 
Steel hull weight =(0.0038 to 0.0037) xCN (cu. ft.) 
(ton) =(0. 1 35 to 0. 1 30) x CN (cu. m.) 

Weights of steel hulls, deck planks, insulation, equip- 
ment and fittings, and machinery are given in table 8 
in the form of percentages of the light weight. 

The longitudinal centre of gravity in light condition is 
aft of midship, due to the position of the engines. It was 



o Long 



13^ 



rtth and depth and length for longltncrs Fig. 70. 
and combination boats 

[79] 



Relation between hull tteel 

* --* 

longwiers ana 



md cubic mmber fir 



PISHING BOATS OF THE WORLD : 2 TACTICS 




"" "LM "* 

Fig. 77. Admiralty constant and froude number versus length for 
lonf liners and combination boats 



3 per cent. LBP aft of midships in the immediate post-war 
boats. The longitudinal centre of gravity is now 7 to 
8 per cent. LBP aft of midships owing to the increased 
weight of machinery in the engine room, weight of general 
outfit in living quarters and a decrease in the weight of 
heat insulating materials. The increased weight of the 
machinery and outfit means that the value KG/D is 
raised to 0.87 to 0.89 against a previous value of 0.80 to 
0.82. 

The maximum displacement of small boats is on the 
outward cruise, and of large boats over 500 GT on the 
homeward cruise. The centre of gravity varies according 
to the load in the holds. At full load it is higher than in 
light condition, and when the fuel oil in the double- 
bottom tank is consumed, counter-measures should be 
taken, such as using water ballast, to get better stability. 

MeUceotre 

The height of the metacentre varies according to the type 



1 

f 

t 



s 




Pig, 72. Motion 



volume offish room and *uHc number for 



UiPllRD 



Fig. 73. Relation between volume offish room, fuel oil and fresh 
water and cubic number for longliners 



of boat but, in general, the following equations are valid 

where T is the mean draught of the boat: 
KB=(0.55 to 0.56) T 

BM, light condition =(0.085 to 0.090)B'/T 
BM, full load condition =(0.090 to 0.095)B'/T 

With 250 to 350 GT ships, every effort should be made 
to maintain a GM of 1.31 to 1.64 ft. (0.40 to 0.50 m.) 
in the most unfavourable conditions. With larger boats, 
the difficulty is lessened by their breadth. 

i^jM^OQy etc 

The main engines should be large to give a high speed, 
so that fish can be landed fresh and command better 
prices. But, with the development of refrigerating facili- 
ties, the question of sailing speed needs to be re-examined. 
Fig. 71 shows the maximum values of V/VL and 
A i/f V'/BHP against LBP at the time of trials. 

Fish room capacities 

The relation between CN and the total hold volume 
of fish holds, fuel oil and fresh water tanks as shown 
in fig. 72 may be expressed as follows: 
Total volume (cu. ft)=0.50 CN-1,766 
(cu.m.)=0.50CN-50 



Percattage weight of 

Item 
Steel hull, % 
D* planking, %. 


TABLE 8 

Longltner 
Below 600 GT Over 6W GT 

43 to 46 43 to 46 
2.5 to 3.4 2.2 to 2.5 


MMMifttfM llMt 

Combination 
boat 

46 to 50 

5 to 5.5 



Insulation, % 

Cork only . 16 to 17 17 to 18 15 to 22 

Oufcttrf !0ex . JO to II 11 to 12 

EOtnflMXMOt AttGl fiw* 

^ % . . 15 to 19 19 to 22 15 to 18 

y,% . 13 to 15 11(013 13 to 15 



190} 



FISHING METHODS AND DECK ARRANGEMENT LONGLINE FISHING 




TABU 9 



-tare 



Fig. 74. Relation between ratio bait hold/ ice hold and cubic number 
for combination boats before and after World War II 



Fig. 73 shows the relation between CN and the fish hold 
capacity of longliners which may be computed from the 
following equation : 



123,600 cu. ft. (3,500 cu. m.) (about 1,200 GT): 
Fish room (cu. ft.)=0.375 CN -3,531 
(cu. m.)=0.375CN-100 

CN> 123,600 cu. ft. (3,500 cu. m.) 
Fish room (cu. ft.)=0.13 CN+31,070 
(cu. m.)=0.13CN+880 

Refrigerating facilities are installed and limit the space 
for the fish hold. 

Fig. 74 shows the relation between the hold capacity 
(bait and ice holds) and CN, and also the ratio of the bait 
hold capacity to the ice hold capacity and CN for com- 



s. 


o 




pf 


^ 




i 

I ' 

i. 






* c 




/ 






tlta* NtrM 
** Vtett 


Mr I 
V.I 

* 


*X 

V"* 

-v 


,_ ... 10 






X 


' 




--- - - * 



- i 





Gross tonnage 


Radius of action 


Type 


GT 


Sea-mite* 


Longliner 


200 to 250 


12,000 to 15,000 




350 


15,000 to 20,000 




Over 700 


20,000 to 25,000 


Combination boat . 


150 to 180 


8,000 to 10,000 




200 to 300 


11,000 to 13,000 



bination boats. The hold capacity may be expressed as 
follows: 

Fish room (cu. ft.)=0.24 CN-8,823 
(cu. m.)=0.24 CN-25 

Ratios of bait tanks to ice hold were 0.6 to 0.8 before 
World War II, when no refrigerating equipment was 
provided, but nowadays most boats have such equipment, 
and hold space is reduced so that the ratio is about 0.8 
to 1 .0. Fig. 75 shows the capacity of the bait hold and ice 
hold space against gross tonnages. 

Tank capacities 

Fig. 76 shows the freshwater and fuel oil tank capacities 
in relation to gross tonnages. The amount of freshwater 
varies according to the number of crew and navigation 
days, but in general, 

Water (cu. ft.)=(l .94 to 3.00) x GT 
(cu. m.)=(0.055 to 0.085) XGT 




- 1 



. 75. Relation between volume of bait hold and gross tonnage for 
combination boats before and after Werld Warll 



Fig. 76. Relation between volume of freshwater and gross 
jfr longUners and combination boats 



FISHING BOATS OF THE WORLD : 2 TACTICS 




TABLE 11 



MS of beats 



Fig. 77. Main engine output of longliners 

There is a tendency towards an increase in these figures. 
Fuel oil (cu. ft.)(12.36 to 15.89)xGT 
(cu. m.)=( 0.35 to 0.45) xGT 

The main engine output of longliners is shown in 
fig. 77, and the radius of action is given in table 9. 

Construction 

Electric welding is generally used, riveting being em- 
ployed only for the seams of bilge plates and deck 
stringer angles, etc. Section building is being widely 
adopted and construction time has been shortened 
remarkably. 

Slamming in the aft engine type of boat is a serious 
problem, and engineers are strengthening various parts 
more than specified in the regulations, although further 
studies are necessary. 

Longliners often cannot be docked for six months or 
longer, and their shell plating is badly fouled, so the sand- 
blast vinyl coating process was introduced to protect the 
hull. 

MACHINERY 
Main engines 

Main engines are 4-stroke, airless injection diesels. The 
power of the engines has recently been increased by 30 to 



Cross tons 
GT 

230 

350 

700 
1,000 
1,500 



Total 



150 
200 
400 
500 
1,000 



50 per cent, by the use of superchargers, with the result 
that, without sacrificing hold space, higher speed and 
longer voyages have become possible. The relations of 
gross tonnage to main engine power are shown in table 
10. 

Engines are expected to run at full speed when a 
shoal of tuna is found, but at only 4 knots when hauling 
lines. Very low revolutions are kept for a long time, with 
clutches in and out. The engines must have the dura- 
bility to stand continuous running for six months without 
overhauls. 

The majority of screws are of the 4-blade, fixed-blade 
type and made of manganese bronze. Controllable-pitch 
propellers are operated from the wheel house by electric, 
hydraulic or rod systems. 

Main engines are controlled from the bridge on some 
large longliners. With controllable-pitch propellers, 
remote control is believed to contribute much towards 
safety, high speed and accuracy of operation. 

Auxiliary engines 

After World War II, the power of auxiliary engines 
increased because of the adoption of freezing systems and 
the increase in cargo capacity. Three generators are 
installed, running in parallel, to supply electric power on 
ships exceeding 1,000 GT. 

Alternating current has been adopted to meet increased 
demands, and it has resulted in reduced costs, more 
flexibility of voltage, ability to take power from shore 
supplies, and easier maintenance. 

Table 1 1 shows the relation between gross tonnage and 
total horsepower of auxiliary engines. 



Nonul 



TABLE 10 

iae 
of 



Gross tonnages 
GT 

250 

350 

700 
1,000 
1,500 



Main engine 
h,p. 

500 

650 
1,200 
1,500 
1,800 



Other apparatus 

Wireless. Communication with the land and with 
other ships is necessary to ensure safety, detect shoals of 
fish, and to obtain information about fluctuations in fish 
prices, etc. Particulars are given in table 12. For com- 
munication between mother and catcher boats, 2-MC 
10 W wireless telephones are installed. 

Radar. With automatic position finders and gyro- 
compasses it is functioning well. 

Echo sounders (fish finders). These operate very satis- 
factorily. 



182] 



FISHING METHODS AND DECK ARRANGEMENT LONGLINE FISHING 



Item 

Transmitter 
Type 

Powerx units 

Auxiliary transmitter 
Powcrx units 

Receiving set 
Shortwave 



Lony and 
medium wave 

Emergency 



TABLE 12 

Before War 

Self-exciting 
100to300Wxl 

None 

4-valve auto- 
dyne xl 

Dittp x 1 
None 



After War 

Pre-tuned crystal con- 
trol system 
lOOtoSOOWxl 



25to50Wxl 

8- to 16- valve super- 
heterodyne or double 
super xl 

Ditto xl 

4-valve autodynex 1, 

or 
8-valve super set xl, 

or 
All-wave set xl 



Thermometers. Tube and electric thermometers are 
installed in each hold to maintain the proper tempera- 
ture, and indicators in the engine room enable the 
engineers to regulate the temperature by means of 
expansion valves. 

Steering devices. Steering angles are large and 
manoeuvring is frequent when tuna boats are fishing. 



The electro-hydraulic system is used on most ships. 
Magnetic compass pilots and remote controls are used in 
navigation for longer voyages. 

Table 13 shows the relation between gross tonnage and 
steering engine power* 



TABLE 13 



Normal 



of boa* 



Gross tans 


Steering engine power. 


GT 


h.p. 


250 


1.5 


350 


1.5 to 2 


700 


3 


1,000 


5 


1,500 


7.5 



Anemometers, logs, helm indicators, tachometers, 
exhaust air thermometers and other electrical measuring 
instruments are used on tuna boats. 

Lifeboats or liferqfts for ten persons were at one time 
required, irrespective of the number of the crew, but 
today the law stipulates that fishing boats must have 
sufficient lifeboats or rafts for the entire crew. As there 
is little space for lifesaving appliances, liferafts of the 
self-expansion type are generally used. 



1831 



POLE AND LINE FISHING: DECK DESIGN AND EQUIPMENT 

by 
SHOGO MURAMATSU 

One of the important fishing methods in Japan is by pole and line. The boats differ in construction, equipment and installation 
dopendingon the species they catch: skipjack, mackerel and squid. 

This paper deals with particular features of these boats, i.e. the fishing method and the resultant deck design, especially the 
water-crinkling device, but tank, electric equipment, steering arrangements and fish hold. <* 

EQUIPEMENT DE PONT POUR LA PECHE A LA LIGNE AVEC UNE CANNE 

La pAche & la ligne avec une cannc est une des principales m&hodes utilisees au Japon. Les navires different dans leur construction, 
Icur 6quipement et fair installation selon les especes pdchees: bonite & vcntrc ray, maquereau et calmar. 

Gette communication traite des caract6ristiques particulieres de ces navires, c*est-&-dire la methode de peche et 1'dquipement de pont 
qiti en dtooute, sptriatement le dispositif de projection d'eau, le vivier & app&t, T^quipement dlectrique, les dispositifs pour gouverncr et la 
cale & poisson. 

LA PESCA CON CAN A Y LIN A: EQUIPO Y FORMA DE LA CUBIERTA 

La pesc* con la cana y lifla reviste gran importancia en el Jap6n. La forma de las cmbarcaciones, el equipo y la instalaci6n varian 
segun se pesque barrilete, caballa o calamar. 

Trata esta ponencia de caracteristicas determinadas de las embarcaciones, por ejemplo: el mtodo de pesca y las formas que hay 
que dar a las cubiertas para practicario, especialmente el sisterma de chorrillos de agua, los viveros, el equipo el&trico, los sistemas de 
gobierno y ia bodega de pescado. 



SKIPJACK* fishing in Japan goes back thousands of 
years, bones of skipjack being found in shell 
mounds of the Stone Age. It is thought that in 
those days they were caught with the bare hands when a 
fish school swam towards the shore. Later they were 
caught with bone hooks, or with horn or bone spears. 
Up to the Edo era (1603 to 1868), the skipjack came very 
near to the shore and fishing was done from conventional 
sail or row fishing boats of small size. In the Meiji era, 
from 1868 to 1912, skipjack migrated more offshore, so 
larger boats were required. Mechanisation began in 1903. 

Modern boats have a fishing platform all around the 
bulwarks, and a huge bow platform. More than one- 
third of the hold has no buoyancy when used for bait, 
because it is open to the sea through the bottom. 

The skipjack fishing fleet, including boats for tuna 
longline and skipjack pole and line fishing numbered, at 
the end of 1954, 1,263 vessels of over 20 GT, the total 
gross tonnage being 142,892 and the average 113 GT. 
Hie average power was 233 h.p. The total catches of the 
fleet amounted to 1 14,000 ton. 

The trips last, according to the size of the boats, from 
5, 10 to 12 days for fishing craft of 20, 50 and over 




Katsuwowu pclamis (Linne). Euthynmu affinis yaito 
Sarda oriental!* (Temminick at Schiefel), and 



100 GT, respectively, with 2, 4 and 6 days fishing respec- 
tively. The duration of the trips also depends, of course, 
on the distance to and from the fishing ground, and 
necessary provisions fuel, fresh water, ice, bait, etc. 
must be carried accordingly. The quantities of ice vary 
according to the degree of insulation of the fish hold and 
size of the refrigeration plant. 

Some attempts have been made to reduce the heavy 
work of angling from fishing platforms and also to 
decrease the large crew. The purse seine was assumed to 
be the best alternative method, and more than ten 
boats were constructed with a large space aft, the engine 
forward, and without the fishing platforms. These purse 
seiners all proved a failure, however, and were converted 
into the traditional type. 

FISHING METHOD 

Before leaving port all possible information is gathered 
on the presence of the fish schools. A sharp look-out 
is kept at sea, the temperature and colour of the water 
are examined, and trolling tests made to detect the 
schools. The best time for finding fish if about sunrise, 
and they seem to bite best in the morning. In general, 
more fish are caught in cloudy weather than in fine, and 
there are more chances of detecting than during A change 
of weather and after the passage of small cyclones. 



[84] 



FISHING METHODS AND DECK ARRANGEMENT POLE AND LINE FISHING 



Fiih arc apt to come to the surface when the wind drops, 
and biting fish arc usually found in dear, tidal waters. 
Upon detecting fish, the boat sails in the direction of 
the school, its formation and movement being assessed by 
trolling. If it is satisfactory, live bait is chummed while 
sailing slowly ahead. When the school rises to the bait, 
the boat stops with its fishing side to leeward. 



Fishing to leeward gives the forward fishing lines more 
range, the constant tension in the lines preventing their 
entanglement. When the fish are abundant and biting 
well, the fishing platforms on both sides of the boat can 
be used. The crew are assigned duties as anglers, 
chummers and bait carriers. The chummers are experi- 
enced and skilled fishermen who throw bait into the sea 
from boxes at the bow, stern and midship to attract the 
fish towards the boat and keep them there. Less experi- 
enced fishermen distribute live bait from the bait tanks 
to the bait boxes for the chummers. Skilled young anglers 
are posted at the bow, and older anglers at the stern, 
as shown in fig. 78. 




Fig. 78. Skipjack pole and line fishing with skilled young anglers 
posted at the bow and older anglers at the stern 



To conceal the shadows of the boat and crew and to 
increase the effect of baiting, sea water is sprayed with 
sprinklers over the sea where the live bait has been 
chummed, so as to make the surface seem alive with small 
fish. 

Each angler has a fishing rod, with live or artificial bait, 
and he fishes either standing or sitting. Sitting gives a 
good balance to the body but restricts action, so that, 
except when the boat is rolling heavily, the standing 
position is usually assumed. The angler holds the rod, 
set in a rod-holder attached to his waist, and the moment 
he feels a bite he jerks it up and catches the fish under his 
left arm to remove the hook. Some men swing the fish 
on board and by a whipping motion of the lines release 
the hook with a snatch as the fish lands on deck. The 
latter method is used mainly with artificial bait. 

Fishing efficiency can be greatly improved with arti- 
ficial bait, which can be used when the skipjack are biting 

very freely. Enough live bait must be thrown out to keep 
the school from dispersing. When the biting becomes 
less active, Hve instead of artificial bait is used. 



When hooking, every possible care is taken not to 
impair the vitality of the live bait. Sardines axe usually 
hooted in the collar-bone, but other fish in the back r 
neck, nose or eye, according to species and size. The rod 
is operated to permit die bait to swim freely in the water* 
When the school disperses, fishing is abandoned md a 
new school sought. A school normally gives from 
10 min. to 2 hr. fishing, and in a few exceptional cases it 
can last for a whole day. 

Fishing gear 

This is quite simple, being merely a bamboo pofe r 
15 to 20 ft. (4.5 to 6 m.) long, fitted with a hemp or cotton 
line 1 to 1.5 ft. (0.3 to 0.45 m.) shorter than the pole* 
The bait hook is 1 to 2.5 in. (25 to 65 mm.) long, and hat 
no barb because a large number of fish are caught in a 
short time and have to be rapidly released from the hook. 
The centre of the jig hook is made of horn, or whale 
bone, and wrapped with a feather. 

Handling the catch on board 

The best and the most generally adopted way of storing 
skipjack during a 10 days 9 trip is to keep them in a light 
brine at about 32F (0C), which prevents drying and 
damage by pressure. The catches piled up on deck should 
be stored immediately, to avoid exposure to the sun. 
When quick storing is not possible, constant sprinkling 
with sea water as well as protection from the sun are 
necessary. The bait carriers, when they are not carrying 
bait, kill the live skipjack and wash them with sea water. 
When the bait tanks are emptied they are cleaned and 
used as fish holds. The holds are partitioned off so that 
fish can be stored by size. After all catches have been 
stored, they are covered with rough hemp or cotton 
cloth, bamboo hurdles, and cement weights, to avoid 
damage by the rolling of the vessel. 

AJbacore fishing 

The pole and line fishing season for albacore in Japan 
starts at the end of July. This is normally combined with 
skipjack fishing because the two species are generally 
found in the same areas. Therefore, skipjack vessels, 
during the albacore season make preparations to catch 
both, because albacore are very valuable for the export 
market. The gear used for albacore is stronger than for 
skipjack, particularly the pole and line. 

For albacore two anglers work together, each with a 
pole having joined lines. The hooked fish is lifted on 
board between the two anglers. Otherwise the method 
is practically the same as for skipjack. The maximum 
size of fish which can, be lifted by a single angler is about 
24 Ib. (11 kg.), whereas two anglers can handle 42 to. 
(19 kg.). Bigger fish have to be lifted on board with a 
gaff hook. 

GENERAL ARRANGEMENT 

Fishing operations for skipjacks and albacore take place 
far out in deep water and often in a high swdl, so the 
hulls must be strong and seaworthy. Moreover, as the 



[85} 



FISHING BOATS OF THE WORLD : 2 TACTICS 



crew often fish cm one side of the vessel, it must have 
good stability. The majority of the wooden skipjack 
boats range from 30 to ISO GT* Steel vessels are mostly 
of the 1 50 to 1 SO GT daw. 

Since most of the skipjack fishing boats are also used 
f or tima in its season (spring and summer) they must have 
a food cruising range and a speed of 9 to 10 knots to 
operate all the year round in far distant fishing grounds 
and facilitate a large number of voyages. 



The hold is divided into 9 to 12 compartment*, with 
the ice holds on both sides and bait tanks in the centre. 
Each compartment has a deck hatch. 

No special fishing deck gear is required, except piping 
and the fishing platforms. 



Their effective width is about 21.7 in. (55 cm.) and they 
have 17.8 in. (45 cm.) high benches. Knee the bow is 





i 



B- 








Fig. 79. General arrangement of skipjack and tuna clipper where no special fishing deck gear is required 



Because of the limited angling time, it is essential to 
have a large crew for whom accommodation must be 
provided Boats of 20 to 50 GT carry on an average a 
crew of 30; 50 to 100 GT boats 45; and boats of over 
100 GT, about 55 fishermen. 

As shown in fig. 79, the boats usually have the engine 
aft, hold forward, and the deck house above the engine 
room* A large number of the crew are accommodated 
in two cabinsone forward, and the other aft of the 
engine room. 



most suitable for fishing, the platforms in this area are 
designed to accommodate as many fishermen as possible, 
to withstand heavy waves, to dnabte the anglers to keep 
in contact with thoee on the other side, and to allow the 
fish to slide to the deck. 

Turbine pumps, belt-driven from the main or auxiliary 
engine, are used for the water sprinkling system. The 
diameter of the pump discharge pipe is 5 in. (127 mat) 
on bays boats; 4 in. (102 mm.) on vessels of medium sue 
and 1.3 in. (33 mm.) for those of smaller size. The 



1*6} 



FISHING METHODS AND DECK ARRANGEMENT ~ POLE AND LINE PISHING 



sprinkler pipe is usually laid over two-thirds of the length 
of the boat, the diameter decreasing towards the stern. 
Hie distance between the sprinkler nozzles is approxi- 
mately 13.8 in. (350 mm.) at the bow, 15.8 in. (400 mm.) 
at the stern and 19.6 to 35.5 in. (500 to 900 mm.) mid- 
ships. On some vessels the pump is controlled from the 
bridge. 

Fig. 80 shows a section of fishing platform and fig. 81 
the water sprinkler machinery. 



Sprinkler 




Ftf. SO. Fishing platform 

Sea water circulates through the bait tank on deck, 
supplied by a turbine or centrifugal pump in the engine 
room. The diameter of the supply pipes is 3 in. (76 mm.) 
for large, 2J in. (63 mm.) for medium and 2 in. (51 mm.) 
for small boats. The same pump is also used for washing 
the deck. The capacities of pumps used on skipjack 
boats are shown in table 14. 

Mate i 

A few typical specifications are given in table IS. The 
hold capacity is huge and the GM is not very small, but 
the freeboard at full load is amazingly small. This last 
characteristic is not conducive to safety. Another out- 
standing feature is the number of crew required and 
consequently accommodation is a difficult problem. 



A 5 kW generator supplied electricity for deck and 
cabin lights, navigation and flood lights. A second 5 kW 
generator is installed for battery-charging equipment,, 
radio, direction finders, Loran and fish finders. 



its. 



Hold 

The main hold is divided into many small < 
There are two longitudinal bulkheads to give one row 
along each side for the ice containers and a centre one for 
the bait tanks, as shown in fig. 79. On the outward 
voyage the containers ait filled with block or crushed ice 
and the tanks with live bait; whereas on the homeward 
voyage all are used to hold fish. 

The capacity, type and location of live bait tanks have 
an important influence on fishing operations. The tanks 
are generally partitioned to keep the bait quiet and to 
prevent excessive water movement. The sea water in 
the tanks is circulated by power or naturally. Power 
circulation requires large pumps, costly piping and an 
auxiliary power unit; so this method is rarely used. With 
natural circulation, the sea water enters freely through 
valves in the bottom of the ship. These valves are plugged 




Fig. 81. Arrangement of sprinkler machinery 



TABLE 14 
Capacity of bait tank 



Type 
Turbine 



Rotiiy 



Diameter 
M* mm. 
2 51 
?* 8 



76 
102 
127 

76 
102 
127 



Dimensions (excluding piping) 

Length Breadth Height 

in. mm. in. mm. in. mm. 

21.6 550 12.4 315 15.9 405 

26.0 660 14.2 360 18.1 460 

29.1 740 14.7 373 18.9 480 

31.3 795 15.9 405 21.8 555 

36.4 925 22.4 569 24.4 620 
30.9 785 11.0 280 13.4 340 
39.4 1,000 13.4 340 19.1 485 
45.8 1,165 18.3 465 214 570 



r.p.m. 
1,700 



f 
5 

7.5 
13 

6.8 
12.5 
17.8 



Disckarrt 
(ton per hr.) 

22 
35 
65 
95 
35 
60 
80 



Head 

&m. 
16 

59.1 18 
65.7 
65.7 20 
65.7 20 
65.7 B> 
65.7 
65.7 20 



[87] 



FISHING BOATS OP'TOIB W0mU> : 2 TACTICS 



Ship'* 

Type of construction 
Year launched 
Shipyard 

Principal dimensions 
L . . . 
B 
D . 

or ... 

Main engine (dieseJ) 
Wirefeas ratonna pow 
Number of avw 

Capacities 
Withhold . 
Pud oil tank 
Fresh water tank . 

Light condition 

Trim by item 

A 

S 

9 



OM 

KOp 
LOO aft |L 



T . . 
Trim by stern 

A 
8 

? 

OM 

KOJp 

LCOaftiL 

Trial rttult 
T . . 
Trim by stem 
A 



ft, (m.) 
ft. (ai.) 

Mm.) 



. h.p. 
. W 



cu. ft (cu. m.) 
cu. ft. (cu. m.) 
cu. ft. (cu. m.) 



ft.(m.) 
ft. (m.) 



ft. (m.) 

. ; 

ft.(m.) 



ft. to.) 
ft. (m.) 
. ton 



ft.(m.) 
. . 
ft.(nx) 



ftfm.) 
ft. (m.) 
. ton 



MyofyoMant 
No. 3 

Steel 

1948 

Kanasashi 



101.38(30.90) 

19.68 ( 6.00) 

10.17 ( 3.10) 

159.85 

320 

125 

65 



5,141 (145.6) 

1,639( 46.4) 

364 ( 10.3) 



5.61 (1.71) 

5.18(1.58) 

183.76 

0.59 

0.65 

0.76 

1.34(0.41) 
0.80 

1.77(0,54) 



9.42(2.87) 

3.15(0.96) 

366.68 

0.69 

0.73 

0.89 



V/Max.iLp. 



-1. 77 (-0.54) 



5.61 (1.71) 

5.91 (1 JO) 

134.00 

9.66/320 

10.05/384 



TABU 15 
of skipjack 

Kotoshiro \faru 
No. 3 

Wood 

1951 

Goriki 

97.77 (29.80) 

20.01 ( 6.10) 

10.33 (3.15) 

153.19 

430 

125 

70 



5,552(157.2) 

1,519( 43.0) 

219 ( 6.2) 



7.38 (2.25) 

6.66(2.03) 

218.89 

0.59 

0.63 

0.76 

1.77(0.54) 
0.77 

5.97(1.82) 



10.50(3.20) 
4.27(1.30) 
360.95 
0.67 
0.70 
0.84 
2.20(0.67) 

0.70 
3.25(0.99) 



7.48 (128) 
6.30(1*92) 

218.00 
10.11/430 
10.61/516 



KaioMeru 
No. 11 

Wood 

1949 

Ntehii 

81.36(24.80) 

18.04( 5.50) 

9.19 ( 2.80) 

97.93 

210 

125 

57 



3,581 (101.4) 
816 ( 23.1) 
258 ( 7.3) 



6.14(1.87) 

6.14(1.87) 

130.91 

0.59 

0.63 

0.77 

1.61 (0.49) 
0.82 

5.25(1.60) 



8.07 (2.46) 

5.51 (1.68) 

200.82 

0.65 

0.69 

0.83 

,.57(0.48) 

4.49(1.37) 



64)7(1.85) 

2.62 (0.80) 

123.20 

8.63/210 

8.76/282 



Ckoei Maru 
No. 11 

Wood 

1950 

Koyanagi 

74.80(22.80) 

16.73 ( 5.10) 

8.04 ( 2.45) 

78.04 

210 
50 
50 



3,147(89.1) 
619(17.5) 
102 ( 2.9) 



4.92(1.50) 

4.92(1.50) 

91.34 

0.54 

0.63 

0.74 
1.77(0.54) 

0.88 
4.72(1.44) 



7.81 (2.38) 

3.15 (0.96) 

171.15 

0.64 

0.70 

0.86 
1.64(0.50) 

0.87 
3.41 (1.04) 



5.09(1.55) 
5.91 (1.80) 

85.20 
9.70/210 
9.77/250 



KoryoMoru 
No. 2 

Wood 

1951 

Yaizu 

68.24 (20.80) 

14.93(4.55) 

7.61 ( 2.32) 

61.03 

160 
50 
40 



1,886(53.4) 
297 ( 8.4) 
138 ( 3.9) 



5.15(1.57) 

5.18(1.58) 

73.99 

0.57 

0.66 

0.75 
1.54(0.47) 

0.85 
3.18(0.97) 



6.63 (2.02) 

4.89(1.49) 

108.75 

0.65 

0.72 

0.83 
2.30(0.70) 

0.63 
2.46(0.75) 



5.38(1.64) 
6.30(1.92) 

78.6 

8.67/160 
8.90/192 



with lead or glass spigots when carrying fish. The 
disadvantage of natural circulation is that the tanks 
cannot hold a large quantity of bait, and the boat 
cannot anchor in muddy waters when she carries live 
bait. Rg. 82 and 83 show a bait tank valve as used on 
boats with ccSing, The total area of the valves is 
of the bottom area of the tank. When the 
bait tank is to be used to store the catdt, the water is 
4ected with a rotary pump thro^h a hose with strainer. 
The pomp can also be used, in an emerfency, for 

IMIk hokb imist withstand a large water head, both 



when they are used for bait and for fish stored in a 
mixture of crushed ice and tea water. The ceiling is made 
from cedar or pine planks of the same length as the 
hold, 1 to L5 ft (a3 to 0.45 m.) wide, and 2 to 3 in. 
(50 to 75 mm.) thick. Skill is needed to make the seams 
and butts completely watertight. There is a reoent 
tendency to use plywood covered with a binding agent 
-+* a lining for Ash hokte, because of its water-resistant 
qualities Refrigeration equipment now commonly 
instated in large vesaeb maintain the temperatures in the 
hoklttabcmt32T(0'QandtheriiM>ntersarehutaHed 
having reconttng dial* in the wheelhouse. 



[88] 



FISHING METHODS AND DECK ARRANGEMENT POLE AND LINE FISHING 



MACKEREL 

The history of Japanese mackerel 41 fishing can be traced 
bade to very remote times and it has developed remark* 
ably since the Edo era, when mackerel were caught by 




\Sto water vulva 
Fig. 82. Section through bait and ice hold 

handlining or with nets. Handlining in those days was 
done at night, using lights, as well as in the daytime. In 
recent years pole and line fishing has been introduced. 
Until about 1948 small boats of under 20 GT were used, 
from September to February, the operation being sub- 
sidiary to fishing for skipjack. Since 1951 pole and line 





I 
.J 



Fig. 81. Sea warn tote, the total area of the valves being about 
one-fifteenth of the bottom area of the tank 

fishing has been conducted all the year round with 
35 to 60 GT vessels. In the southern part of Japan, 
boats of 100 to 135 GT are now often used. 



FISHING METHOD 

Catching mackerel with pole and line is similar to 
skipjack fishing, except that the trips are shelter and a 
larger crew is required for mackerel. Further, the bait 
consists mainly of frozen sardine, saury or herring, 
packed in 34 Ib. (15 kg.) cases. Hie quantity of the bait 
is 10 per cent, of the weight of the catch expected with it 
Mackerel is caught by night, and boats go to the 
fishing grounds in the evening to investigate the move- 
ment of the schools with echo sounders* At the same 
time fish-luring lamps are hung over the side, and frozen 
bait is chopped and distributed to the bait boxes of 
each angler. The fish, attracted by the lights, come to 
the surface and try to bite the bait, when the fishermen, 
with a quick swing of the pole, hooks it indiscriminately 
and hauls it up. 




fig. 84. Mackerel pole and line fishing boat 

When fish are found in deep waters, the anglers first 
use hand lines and shorten them as the fish gradually 
come up to the surface (fig. 84). Immediately this 
occurs, the anglers change to pole and line, while bait Is 
chummed, or scattered, on the surface. Young anglers 
are seated in the bow with veterans aft, on both sides, 
facing astern. The pole is held in the outboard hand and 
a dipper in the other, and as the angler scatters chum 
with the dipper, he moves the hook bade and forth 
through the water, inducing the fish to bite. While 
keeping the boat to the wind, the master adjusts the 
speed so that the boat stays with the scattered bait 
When the school is very dense all anglers fish on one side 
of the boat standing up. Bah chumming is of mq$or 
importance in this type of operation. The bait is brought 
to the anglers when they are fisfcing by four or five bait 
carriers on each side pf the boat, and the anglers scatter 
it as evenly as possible. 



This consists of pole, tine and hook. Hie pole is about 
3 .3 to 6.6 ft. (1 to 2 rau) long; the line is made of synthetic 
fibre of almost the same length as the pote, with one 

is also necessary. 



FISHING BOATS OF THE WORLD : 2 TACTICS 



TABLE 16 



Mb* Length Width Height 

2 in, 21.4 12.8 13.2m. 

51mm. 545 325 335 mm. 



Discharge 



4.5 02 to 0^8 in. 
5 to7 



250 

3 in. 29.5 15.3 16.3 in. 150 to 7.5 0.28 to 0.36 in. 
76 nun. 750 390 415 mm. 200 7 to 9 mm. 



Theelccti 



itallation docs not differ much from that 



of skipjack pole and HIM craft. However, a rather power- 
ful generator is necessary to supply the fish-luring 



lamps, since one such lamp is required for every two 
anglers. Normally 20 kW generators are installed for 
this purpose on the large boats, a IS kW generator on 
medium, and one of 10 kW on a small boat* 

Handlfe* the catch on board 

Three methods are used to preserve the catch namely 
(i) ice; (ii) chilled water and (iii) salt. With ice about 
35 mackerels are packed in boxes and covered with 
crushed ice. In small boats, where the capacity of the 
hold is limited, the catch is usually preserved in chilled 
water; the hold being filled with sea water and having its 
temperature lowered by adding crushed ice before putting 
in the mackerel. Mackerel in ice or chilled sea water will 



TABLE 17 



Ship's 

Typo of construction 
Year launched 
Shipyard . . 



KyowaMaru 
No. 8 

Wood 

1958 

Yaizu 



Kyowa Maru 
No. 5 

Wood 
1956 
Yaizu 



Kyowa Maru 
No. 3 

Wood 
1952 
Yaizu 



Toyokuni Maru Shomba Maru 



Wood 
1950 
Yaizu 



Wood 

1948 

Showa 



L 

B . 

D . 

OT . 

Main engine (diesel) 
Wireless antenna power 
Number of crew 

Capacities 
Fish hold . 
Fuel oil tank 
Fnth water tank 

Uqht condition 

Trim by item 
A 

8 



GM 

KO/p 

LCGaftiL 

Full load condition 
T 
Trim by stern 

A 

a 

9 



OM 
KO/D 
LOG alt *L 

Tried remit 
T . 
Trim by stein 

' 



ft. (m.) 
ft. (m.) 
It On.) 



h.p. 
W 



cu. ft. feu. m.) 
cu. ft. (cu. m.) 
cu. ft (cu. m.) 



ft. 
ft. 



ton 



ft.(m.) 
Mm.) 



ft (in.) 
ft On.) 
. ton 



ft (m.) 
ft (m.) 



ft (at) 

ft.(m.) 

ton 



V/Max h.p. 



88.194 

5.1 

9.88 ( 3.01) 
132J1 

380 
80 
60 



3,740(105.9) 

1 , 052 ( 29.8) 

251 ( 7.1) 



6.82(2.08) 

8.60(2.62) 

182^4 

0.61 

0.67 

0.80 

1.97(0.60) 
0.805 

7.12(2.17) 



8.58(2,62) 

3.25(0.99) 

261.33 

0.66 

0.71 

0.87 
1.87(0.57) 

0.765 
6.30(1.92) 



7.48028) 
84)1 (2.44) 
20550 
10.11/380 
10.40/456 



80.38 (24.50) 

17.72(5.40) 

9.02(2.75) 

96.94 

350 
50 
60 



2,861 (81.0) 
1,022 (28.95) 
201 ( 5.7) 



6.43 (1.96) 

6.56(2.00) 

141.91 

0.59 

0.66 

0.82 



6.92(2.11) 



'8.66(2.64) 
4.13(1.26) 
225.28 
0.66 
0.72 
0.91 
1.87(0.57) 

0.75 
3.87(1.18) 



6.27(1.91) 
5.84(1.78) 

135J 
10.27/350 
10.90/420 



68.14(20.77) 

15.16 (4.62) 

7.58 ( 2.31) 

64.04 

180 

75 
45 



1,614(45.7) 
356 (10.1) 
124(3.5) 



4.59(1.40) 

5.31 (1.62) 

70.36 

0.55 

0.64 

0.74 

2.07 (0.63) 
0.76 



6.56(2.00) 

2.46(0.75) 

116.3 

0.65 

0.70 

0.83 

1.67 (OJ1) 



64.63 (19.70) 

13.98 ( 4.26) 

6.17 ( 1.88) 

37.48 

120 
40 
32 

1,052 (29.8) 
215 ( 6.1) 
989 ( 2.8) 



4.72(1.44) 

5.91 (1.80) 

60.66 

0.56 

0.68 

0.73 
1.05(0.32) 

0.90 
4.23(1.29) 



5.91 (1.80) 
2.76(0.84) 



SM (1.65) 
5.58(1.70) 

86JO 
8.90/1W 
9.11/216 



0.61 
0.70 
0.78 

1.18(0.36) 
0.81 

1.51 (0.46) 



4.99(1. 



64.60 
8JOSV120 
8^6/142 



54.89(16.73) 

11.02( 3.36) 

5.31 ( 1.62) 

19.50 

75 
20 
29 



795 (22.5) 

117( 3.3) 

71 ( 2.0) 



3.64(1.11) 

3.44(1.05) 

33.97 

0.64 

0.68 

0.78 
0.72(0.22) 

0.84 
4.99(1.53) 



5.31 (1.62) 

0.33 (0.10) 

58.86 

0.70 

0.73 

0.84 
0.79(0.24) 

0.74 
1.25(0.38) 



4.59(1.40) 

2.62(0.80) 

4tfJO 

7.44/75 
7^9/90 



[90] 



fish is salted. This method, however, requires t large 
deck space. 



FISHING METHODS AND DECK ARRANGEMENT POLE AND LINE FISHING 

drifting too much to leeward To facilitate this, the 
vessel normally carries two large spankers, as shown in 
fig. 85, on the mizzen matt, which prevent the rather 
high bow from yawing. The size of the spanker in large 
vessels is about one-third of the wind profile. Sometimes 
it is also necessary for the same reason to reduce the 
the freeboard forward by filling the forward fish holds 
with water. 

In order to have full control of the rudder movements, 
the connection between rudder and wheel is by direct 
shaft. Some boats have recently been fitted with hydraulic 
steering gear. 

Bait chopper 

Mackerel vessels are also fitted with a chopper driven by 
belt or chain from the main or auxiliary engine with 
characteristics according to table 16. 

Main specifications 

A few typical examples of mackerel boats are shown in 
table 17. 

Hold design 

This is practically the same as in skipjack pole and line 
fishing boats, the only difference being that mackerel 
boats have no sea water valves because live bait is not 
necessary for mackerel. 

SQUID 

Squid is one of the most popular fish in Japan. They are 
caught in all the coastal waters, especially on the Pacific 
side, and constitute about 10 per cent, of the Japanese 
fish catch. The pole and line boats used for squid are 
mostly 6 to 20 GT, with motors ranging from 10 to 
30 h.p. They are of the Japanese type, and are equipped 
with fish-luring lights, three such lamps being fitted on 




Fig. 85. Mackerel pole and line fishing boat with wheelhouse aft for 
control of operation. The vessel is also fitted with a spanker sail 



GENERAL ARRANGEMENT 

Most of the small mackerel boats, up to 30 GT, are of 
modified Japanese type incorporating foreign ideas. The 
boats have straight sides and bottom with a chine, 
providing a streamlined water flow from stem to stern. 
As shown in fig. 85, the wheelhouse is placed at the stern 
to enable the skipper to control the whole operation and 
see both the crew and the effect of the chumming at the 
same time. The wheelhouse aft also helps to keep the 
bow into the wind. 

During the fishing operation the catch is collected on 
deck amidships. To prevent it from sliding astern, the 
deck has an upward sheer from midships to aft. Such 
sheering is, however, impracticable on larger vessels, 
so these have pond boards to stop the fish from moving 
on the deck. 

FieWng pUtf orws 

These are more or less the same as in skipjack boats. 
The anglers generally fish in a standing position, but 
when the schools are not very dense they sit on fishing 
seats on either side of the boat, facing towards the stem. 
Each seat has a board which can be set up as a shelter, 
both from the wind and also from the bait that is being 
scattered by the forward anglers. The seats for mackerel 
fishing are, therefore, slightly different from those used 
on ikipjack boats. 

With mackerel pole and line fishing, it is not necessary 
to sprinkle the sea with water, nor are bait tank circula- 
tion and draining needed; so pumps are only required 
for deck-washing and bilges. In some of the large 
mackerel boats, however, motor pumps have recently 
been installed to unload the catch by pumping. 




Fig. 86. Squid hantf lines, with 



a mackerel pole and tine shown extreme rig 



hook*,w*h 



The vessel must be kept head to the wind without 



each side of the vessel. A crew of about 15 is carried. 
Squid fishing is also conducted in-shore from smalt 
open boats with one or two anglers. 

In peak seasons various small craft, normally used for 
other purposes join the squid fishing fleet. 



[91] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



FISHING METHOD 

Good fishing grounds for squid are generally found in 
waters 2 to 4 miks from the coast at a depth of about 
20 to 75 fra. (35 to 135 m.). The squid swims nearer the 
surface in the summer than in winter, and it also goes 
to shallower water in warm weather. The fishing opera- 
tion itself is very simple: on arrival at the ground, the 
vessel stops and fishing starts and goes on for 1 to 3 hours. 
Dawn and dusk seem to be the best time for squid. 
The handlines are moved up and down at various depths 
until a "biting" depth is found. The squid is then lured 
to the surface by gradually shortening the lines, after 
which shorter handHnes are used, which increase the 
angling activity. Skilled fishermen can handle two or 



more sets of this gear at ooe time, and one man can catch 
about 1 ,000 to 1 ,500 squids hi a night. 



Squid is mostly caught in the evening and before day- 
break with the aid of lights. Three kinds of gear are used, 
namely (i) hanegu; (ii) tombo and (iii) yamade. The 
hanegu gear is used for squid swimming near the surface, 
the tombo for those in mid water, and the yamade for 
those in very deep water. The hanegu gear used in 
Hokkaido consists of three parts, the hook, the synthetic 
line and the pole, as shown on the right in fig. 86. The 
hook itself consists of about 10 brass hooks arranged in 
the form of a small parasol, fastened to the line and baited 



Type of construction 
Principal dimensions 

B ; 

D . 
OT 

Main engine 

Type of main engine 

Wirckw antenna pow< 

Capacities 
Ftohoid 
Fuel oil tank . 
Fresh water tank 

Ufht load condition 

Trim by stern 
A 

8 . 

9 

. 

OM 

KG/D 

LCGaftJL 

Full load condition 
T . . 

Trim by stern 



9 

GM 

KG/D 

LCGaftIL 

"Dial result 
T . 
Trim by stern 

V/100%kp. ! 
V/Max. h.p. , 



TABLE 18 

Mate specifications of iqukl fishing boats 
Wood 



ft. (m.) 
ft. (m.) 
ft. (m.) 



. h.p. 



W 



cu. ft. feu. m.) 
cu. ft. (cu. m.) 
cu. ft. (cu. m.) 



ft. (m.) 
ft.(m.) 
. ton 



ft. On.) 
ft.(m.) 



ft.fm.) 
ft.(m.) 
. ton 



ft. (m.) 
ft.(m.) 



ft. to.) 

(Mm.) 

ton 



68.86(20.99) 

14.1 1( 4.30) 

7.15 ( 2.18) 

48.88 

115 

semi-diesel 
35 



1,861 (52.7) 

233 ( 6.6) 

53 ( 1.5) 



4.89(1.49) 

3.48(1.06) 

64.91 

0.54 

0.63 

0.74 
1.77(0.54) 

0.76 
3.84(1.17) 




5.340.63) 
5.71^4$ 

8.10/115 
8.30/125 



Wood 

62.76(19.13) 

13.25 ( 4.04) 

6.40 ( 1.95) 

32.27 

115 
semi-diesel 



1,342(38.0) 

120 ( 3.4) 

32 ( 0.9) 



4.53(1.38) 

4.33(1.32) 

51.64 

0.56 

0.62 

0.77 
1.71 (0.52) 

0.80 
4.79(1.46) 



5.58 <U 

1.64( 

73.02 

0.61 

0.67 

0.83 

1.35(0.41) 
2.56(0.78) 
1.57(0,48) 



463 (1,41) 
4.20(1.28) 

53.76 
8.14/115 
8.31/125 



Wood 

51.97(15.84) 

11.68( 3.56) 

5.64 ( 1.72) 

19.97 

50 

semi-diesel 



600(17.0) 

64 ( 1.8) 

7(0.2) 



4.10(1.25) 

2.69 (0.82) 

24.89 

0.50 

0.58 

0.73 
1.15(0.35) 

0.90 
1.84(0.56) 



5.38 (1.64) 

1.18(6.36) 

41.24 

0.54 

0.61 

0*80 

1.44(0.44) 
2.53 <y77) 
0.33 (0.10) 



7.10/50 
7.33/60 



PISHING METHODS AND DECK ARRANGEMENT POLE AND LINE FISHING 

with slices of squid. In the other two types of gears, the 
hooks arc fashioned AS shown on the left in fig. 86. 

GENERAL ARRANGEMENT 

The boats have the engine aft, a small fish hold forward 
and the crew quarters aft, as shown in fig. 87. The hold 
immediately in front of the engine room is often used for 
crew accommodation, being fitted with a removable 
entrance. The fishing platform is built on the bulwark 
around the rear half of the boat, and on the fishing 
ground a removable platform is rigged around the bow. 
The fish boxes are piled on deck on the outward voyage. 
About eight fish-luring lamps, each of 1 kW, are hung 
from the spar slung between the fore and mizzen mast. 
The main engine is stopped when fishing, and a sea 
anchor is dropped. 




Fig. 87.' Squid pole and line fishing boat with engine aft 



Main specifications 

A few typical examples of squid fishing boats are given 
in table 18. 



193 J 



NON-TRAWLING FISHING METHODS DISCUSSION 



MR. S. J. HOLT (FAG): Turkey has one research trawler and 
two small vessels carrying on experimental work; Belgium has 
trawlers; Eastern Germany has several research vessels; so 
has Poland; research in Portugal is carried out from the 
Gil Earns, the hospital ship of the dory fleet; Spain has a 
small vessel; die U.S.A. has several research vessels operating 
in the North Pacific. The Chinese Peoples Republic is 
conducting oceanographic studies and probably has one or 
more research vessels; India, on the other hand, does not yet 
have a research vessel; the Union of South Africa has several 
such as the Afrikana; Australia has a small vessel for experi- 
mental work. 

The rastrelliger fishery in the Gulf of Thailand is carried 
out with the aid of a large carrier fleet possessed by Thailand. 

MR. JOHN PROSKIB (Canada) : Hardy's paper is interesting and 
stimulating. There are, however, feveral omissions of impor- 
tant Canadian fishing boats in fig. 1. For example, the 
following important existing types have been omitted: On the 
Atlantic coast, the whale catcher, the trawler (Grand Banker), 
longliners and sardine and herring carriers. 

Of the boats listed in Hardy's paper, the Grand Banker 
dory schooner (longliner) is now relatively unimportant and is 
on the way out In 1957 only 18 of these boats operated out of 
the Canandian Atlantic ports and accounted for less than 
4 per cent, of the total groundfish landings in that year. On 
the other hand, the modern longliners (which do not use 
dories) in 1957 accounted for nearly 7 per cent, of the total 
groundfish landings (except halibut), 65 per cent, of the sword- 
fish and 40 per cent, of the halibut landings. 

In Canada the modern longliners are not one-purpose 
boats besides fishing for groundfish by longline technique, 
these boats are also used for swordfishing (where longline gear 
is not used) and also for mackerel seining. Another recent 
development is the * 4 trapper-longliner" which uses trapping 
and longttne technique for capturing fish. These boats have 
been developed in the province of Newfoundland. 

The sardine and herring carriers (packers) are important in 
the Bay of Fundy fishery and play a dominant role in the- 
weir fishery of the area. 

On the Pacific Coast the important fishing boat types 
omitted from Hardy's table are the whale catcher, drifter 
and longliner. Drifters are important salmon boats and the 
longJiners play a dominant rote in the halibut fishery. 



MR. H. KJUSTJONMON (FAO, Rapporteur): The advent of 
nylon in the last few years has given a new impetus to gillnet 
fishing in many countries where it was waning before, and 
due to this gillnets are now frequently used on big boats, 
up to over 100 GT. The big boats fish in rough weather 
and this make* it more important to locate the power gurdies 



for hauling the nets and longlines near the point of minimum 
movement due to pitching and heaving of the ship. This is 
more critical in the rough Northern seas than it is on the tuna 
longline vessels operating mainly in equatorial waters, and 
this is indeed to some extent reflected in present day practices. 
The Japanese tuna longline vessels normally have the line 
haulers fairly far forward, while the tendency in Scandinavian 
boats, fishing with bottom-set cod gillnets and longlines, is to 
locate the net and line haulers near midships. Power gurdies 
for hauling gillnets and longlines are sometimes placed far 
forward on the assumption that the boat is pulled towards 
the gear. This is a fallacy. Even when fishing with small 
motorboats it is important to manoeuvre the ship under power 
in such a manner that the nets or lines are lifted nearly 
vertically up from the bottom. From the wheelhouse the 
skipper must naturally have a clear view of the hauling opera- 
tion and be able to see the direction of the gear coming up. 

Oillnetting and the other methods of fishing mentioned 
above are very often carried out from combination boats, due 
to the short seasons for each gear. This means that certain 
compromises have to be made as to deck arrangement and 
also the ways and means of providing shelter for the people 
hauling the gear. On the American Great Lakes gillnet boats 
the deck is totally covered, and de Wit has suggested in his 
paper a rather radical design that also provides full shelter 
for the men while hauling drift-nets. Other more improvized 
shelters can no doubt be provided on many of the one-purpose 
or combination boats. It is becoming ever more important to 
give attention not only to labour saving, but also to labour 
easing to make work on the boats more attractive. In many 
countries where industry offers steady and comfortable 
employment on land the fishing operators find it increasingly 
difficult to attract people to work on their boats, unprotected 
on the open deck. 

It should be easy to give much more shelter than is done 
today. There is no need for this hardiness that is expected of 
the fishermen, and furthermore it is wasteful from the point 
of view of efficiency as the men tire less and work better in 
shelter than when wet and cokl and encumbered by heavy and 
stiff seaclothes. 

More fish is caught by purse seining than by trawling or any 
other single method of fishing. As long as the net is operated 
from auxiliary purse seine dories, at in the U.S. menhaden 
fishing, the New England mackerel fishery and the Norwegian 
and Icelandic herring fisheries, any type of boat can be used 
as the main or carrier vessel. The boats in Norway and 
Iceland are multi-purpote boats. The Icelandic (met (Tomaa- 
sonJ955)flih with longlines, bottom-set gillnet*, drift-nets for 
herring, purse seine* and trawis. Cargo vessels of up to 7,000 
tons have been used as purse seine ships, carrying in davits 
everal pairs of mechanized net dories about 30ft (9.15 m.) 
long. 

When the net is operated from the main boat special 



194} 



NON-TRAWLING FISHING METHODS DISCUSSION 



demands aie however, made on design ai>d deck airangemcnt. 
This has been canted to its most rational conclusion on the 
U.S. Pacific Coast (Hanson, 1955). 

Schmidt's paper on pone seining arrived too late to be 
presented at the Congress. This was most unfortunate as it 
would no doubt have hdped to stimulate very useful discussion 
on purse seiners which have not yet received the attention 
from naval architects which these boats merit as die biggest 
fish producers. 

When purse seines are hauled by hand, 12 to 20 men are 
needed. This waste of man power is now becoming critical 
even in countries where wage levels are not yet up to Ameri- 
can or Scandinavian standards. It is therefore essential to 
introduce mechanical labour saving devices and to modify the 
boats accordingly. 

The latest innovation for handling purse seines is the 
powered Mock, which has come into prominence since 1953. 
Schmidt (1959) has also proposed ways and means of modify- 
ing several conventional boat types (with the wheelhouse aft 
or midships) for use with the powered block. The powered 
block is indeed a revolutionary labour saving and labour 
easing device, which makes it an easy task for 6 or 7 men to 
handle a big net. 

Purse seining seasons are often short so combination 
boats are usually called for. One advantage of the powered 
block method is that it can even be applied in the net dories, 
thus leaving the main boat unaffected. This is mainly an 
advantage when mechanizing net handlings on existing boats 
with too small deck space aft. It is however often desirable 
not having to operate with net dories but to handle the net 
directly from the main boat. This can only be done con- 
veniently where there is ample free deck space aft or on the 
quarter for stacking the big net. There are many other strong 
arguments in favour of free deck space aft. This is the driest 
and most sheltered part of the ship and the stablest working 
platform; apart from purse seining, the gillnet, drift-net, and 
longline boats operate ever greater quantities of gear which 
should preferably be stacked on the after deck for setting at 
high speed over the stern. 

A great deal more thought must be given to evolving more 
rational deck layouts and this must go hand in hand with 
work studies on board the boats during fishing operations. 

Drift-net and gfflnet fishing 

MR. J. O. DE Wrr (Netherlands): The Netherlands have 
specialized in drifters. In former days the drifters were sailing 
vessels and in the twenties the whole fleet became motorized. 
The engines were mostly of the hot bulb type of 60 to 80 h.p. 
The vessels were only used during the herring season from 
May to December. In the remaining months, the ships were 
idle. From 1940 there was a growing tendency to use the 
vessels all the year round. This could be done by trawling in 
the winter months. The only objection was that engines of 
60 to 80 h,p. were too small From that time engine power has 
increased steadily to about 1,000 h.p. 

The compromise engine for trawling and drift-net ting would 
be of about 400 h.p. If the output is higher, it is better to 
trawl only, also during the herring season. If the output is 
lower than 400 tup. it is possible to drift during the herring 
season and to trawl during the winter months. 

It becan^ckar that a 141. 1ft (43m.) vessel is not the right 
vesed for drtft-netting and trawling. Hiese vetsels equipped 
with engine from 600 to 1,000 h.p., operate in the North 
Set, the Channel, and recently, south of Wand. It is this 



type of vessel that might be called the Netherlands near and 
middle-water trawler. 

There are two types of nets used in drifters. They require a 
little different handling, though the arrangement on board the 
ships can be the same tot both methods. In case the herring 
is expected to swim high the fishermen use nets above the 
warp. If they swim deep, the nets are suspended from the 
warp. The length of a fleet of nets is about 8,200 ft. (2,500m.) 

Most of the drifters are about 40 years old, and much 
thought is given to their replacement. Up to now replacement 
meant scrapping the drifter and building a middle-water 
trawler. Therefore the drifters and consequently drift-netting 
will gradually disappear. 

Still there are people believing in the construction of new 
drifters. If they are built, they shall always have to be able to 
trawl and to drift; this combination will be inevitable. He 
felt that it will be possible to trawl over the stern on vessels of 
the drifter type and so he tried to combine drift-netting and 
stern trawling. He was fully aware that this point is open to 
discussion. 

MR. W. ORSZULAK (Poland): de Wit stated that the upper 
limit of a drifter was considered to be about 118 ft. (36 m.). 
Studying the problem of the future Polish fishing fleet, three 
main types of ships had been found to meet the requirements of 
bringing fish to the market in the needed amount and quality. 
They were: 

Processing and freezer trawlers of about 1,000 to 2,000 
tons d.w. 

Freezer trawlers of about 1,000 tons d.w. 

Deep-sea drifter-trawlers for salted herring (about 
350 tons d.w.) 

The size of the last mentioned ship (length overall about 
165 ft. or 50 m.) has been discussed with Polish fishermen, 
and they found it possible to operate a drifter of this length. 

He would appreciate it if de Wit could give htm a more 
detailed explanation about the elements limiting the size of 
drifters to the said length. He mentioned that it was proposed 
in Poland to install diesel-etectric drive and a bow rudder 
based on the water jet principles. 

The sketch of the proposed drifter-trawler in de Wit's 
paper seems to have as main disadvantage the proportion of 
the profile areas. The size of the mizzen sail to keep the ship 
against the wind will probably be too large for efficient 



SIR FRED PARKES (U.K.): He was also interested in drifting. 
One of his vessels had won the Prunier trophy twice and he 
found it interesting to note that the vessel which won the 
prize five or six years ago, had twice the herring catch of the 
one that brought home the trophy last season. Wiry, he 
wondered, was herring scarce in the North Sea? Why the 
reduced catches? Herring drifters were hardly built any more 
because of scarcity of fish, and many of the old ones wore 
being converted for various other tasks. What could be done 
to preserve the herring as food for human beings? 

MR. T. Mrraui (Japan): de Wit is of die opinion that the 
qualities necessary for drift-netting wouldbelost if the length 
of die boat is over 118 ft. (36 m.) approximately. The sea- 
keeping qualities would of course be improved as the si of 
the boat becomes larger and the duration of the operation 
could become longer. In his opinion the manoeuvrability 
could be improved by using a controllaWe-pitch 



[951 



FISHING BOATS OF THS WORLD : 2 ^ TACTICS 



tow rodder, propeller rudder, ete. He would wy much 
appreciate if de Wit would elaborate on these details from 



W. DICOON <U.K.): DrSt-aettfag is done by Scottish 
toats mdeep water a* wefi as shallow water, with strops 
between the top of the net and the buoys. The limit for the 
is about 20 to. (36 m) between the buoys and the float 



Drifter-trawlers are not the only possibility for dual purpose 
Drifter-seiners and drifter-tontfiners also offer possi- 



Seining in this context means Danish seining, fly 

dragging style* The biggest drifter-seiners are about 75 ft. 
(23m.) long with 150 h.p. engines. Although these boats were 
intended to be dual purpose, the tendency has been for them 
to remain on one job or the other because of crewtng diffi- 
culties. The other possibility is drifter-longliners of 75 to 
90 ft. (23 to 27 m.) length with 150 to 300 h.p. engines. The 
drift-netting arrangement it the usual one, but some of these 
boats are rigged for both types of fishing at once. They shoot 
the nets and if the fishing is good they return to port; if not, 
they lay the longlines and then continue fishing until a good 
catch is obtained. 

A few 75 ft. (23 m.) boats are now converting to trawl and 
the usual deck arrangement is to have the trawl winch forward. 
This is the easiest form of conversion to make, but not the 
most satisfactory because of the inconvenience in handling the 
fear from a trawl winch up at the bow. 

Another combination boat suggested is the seiner-trawler 
with the winch aft of the casing with dear deck space aft. 
This, however, is not quite satisfactory for drift-netting. 

A 73 ft. (22.3 m.) research vessel of this style is now in 
operation in Scotland. Trawling can be done from the side 
or from the stem, and seining is done from the stem. This 
type has no arrangements for handling heavy gear over the 
stern, 10 that only light gear is worked over the stem; heavy 
gear is worked over die side. It is quicker to shoot and haul 
the net over die stern, but in rough weather it is easier to 
handle from the side. When operating from aft, the crew 
apace has been shifted forward, which is not satisfactory to the 
craw; this is ft real problem. 

PROFESSOR A. TAKAOI (Japan) : Drift-netting for herring is not 
practised much in Japan, but drifters of 66 to 82 ft. (20 to 
25 m.) long, with 250 to 340 h.p. engines, are used to a large 
extent for salmon and trout. About 30 tons of synthetic fibre 
net are shot from the stern, and hauled forward. Only 
small boats are used in Japan, for economic reasons. Salmon 
and trout drift-netting may not be common in other countries 
but this type of boat could be used for other purposes. 

ME. I* G. OB Wrr (Netherlands): He considered the bow 
rudder an essential part of the equipment of a drifter. Hie 
cotttroflabie-pitch propeller and the propeller rudder are very 
helpful but not essential. 

If th&vessd gets longer, the absolute foroes on such vessels 
due to the wind and waves become also of great magnitude. 
Thoce fotttt be balance between these forces and the strength 
of the par. Drift-net* a very tender. With the materials now 
to use, fee Dutch fishermen are of the opinion that vessels 
cnOTwfing 113 ft (36 m.) LBP will increase the net damage. 

As he pointed out in Ms paper, one of the Dutch builders 
isfoingtobuikla 126ft, (3.5m.) LBP wssel. In giving the 
diminishing the wind area, by build- 



tngthe vessel light and by using inodera and stronger materials, 
one can pass this limit tte main objection against His 
proposal is the large wind area, requiring a very large mizzon 
sail if it is not possible to use water jet bow rudder for in- 
stance, as Orszulak suggested. 

He would like to say that diesei-eiectric drive is ideal from 
a technical point of view also for drifters. But he is convinced 
that it is too expensive for this type of vessel with decreasing 
catches, as Sir Fred Parkes pointed out 

Kris^onsson touched the problem of offering more shelter 
to the fishermen and better accommodation because there is a 
growing difficulty to recruit people for the industry. It is his 
impression that more shelter whik working means poorer 
quality of the sleeping accommodation in many cases. The 
quarters will be in the foreship while the best place is aft. 

Regarding the Scottish type nets mentioned by Dickson, 
he thinks the main reason for using them is not fishing in 
shallow waters, but catching the herring swimming nearer to 
the surface. 

MR. H. I. CHAPELLE (U.S.A.): The use of a deckhouse cover- 
ing the whole deck of a fishing boat as described by Colvin is 
unusual. This is not practical in all fisheries carried on in 
cold weather, for reasons of gear used. Nevertheless the ark- 
type deckhouse would have advantages in some instances; 
some New England fishermen found the last winter sufficient 
excuse to consider additional shelter for the crew working 
on deck. 

The deck-layout of these gillnet boats seems to give the 
maximum working space, considering the average size 
and deck machinery required. The windage of the ark-type 
deckhouse is important. As shown in fig. 54, a reduction is 
possible by lowering the working deck to the greatest possible 
degree ; considering the form of body in V-bottoms, placing the 
deck below the chine elevation sharply reduces the working 
platform width. Ballast is necessary in these boats because of 
the limitation just mentioned. As Colvin has indicated, the 
Great Lakes fisheries are in process of change, and so are the 
boats used. It is probable, therefore, that the boats of the 
designs shown in fig. 53 and 54 with ark-deckhouses will be 
replaced by types somewhat similar to fig. 55 and 56. 

The replacement of the round-bottom with the V-bottom, 
in the types represented by fig. 53 and 54 does not appear to 
have resulted in any improvement in hull-form resistance- 
wise. The proposal to employ a fast planing hull in a fishery 
should be of interest. Obviously, the practicality of this is yet 
to be proven, so far as economic operation is concerned. Let 
us hope we may have a report on this matter in due time. 

So little has been published on the Great Lake gillnet boats 
that they are almost unknown outside their area of use. 
Colvin's paper is therefore most useful, particularly as it 
gives an adequate description of a highly individualistic type 
of U.S. fishing boat 

MR. J. H0ISGAARD (Denmark): An interesting gillnet hauling 
winch is shown in Colvin's paper. This Crossly-type net 
hauler is more automatic than the conventional ones used, for 
instance, in Scandinavia. The net is gripped by finger-like 
damps actuated by an eooentiic. No man is therefore needed 
to haul the net off the gurdy as is the case with an ordinary 
vertical net hauler with pressure-groove sheave. He under* 
stood that these net haulers are used extensively in die 
American Great Lakes gillnet fishery but not to ay groat 
extent elsewhere, except that he had heaixl thai some erf the 



CM] 



NON-TRAWLING FISHING METHODS -DISCUSSION 



Russian herring drift-act vessels operating in the North 
Atlantic are now equipped with such, or similar, winches. 
In U.8 A. these winches are normally driven by a separate 
mall engine but a hydnuiHc drive could also be used as 
security tignfofft tmfflfog loo hard on die net. Even though 
these net haulers are rather costly, about 400 (about $1,100), 
they should be tested in European waters and, if found 
suitable, their use should be economic if they save one man. 



MR. E. BBAUDOUX (France): He asked five quest ions: 

Are the Japanese health and safety regulations for 
refrigeration apparatus on board tuna longlincrs the 
same as those of other countries? 

Direct expansion system of ammonia in the fish storage 
holds seems to be authorized in Japan, whereas it is 
prohibited in France. Is this procedure more widely used 
in Japan than brine circulation ? 

The installation of compressors in the engine-room makes 
more space available, but is prohibited in France for 
safety reasons. A separate room is required in France. 
Is it permitted to have refrigeration machinery in the 
engine-room in Japan ? 

Are there any longliners equipped with propulsion 
motor rating between 750 and 1,500 r.p.m.? 

Are there any longliners equipped with air-blast refrigera- 
tion holds? What is the opinion as to this system? 

MR. Y. KANASASHI (Japan): The answers to Beaudoux's 
questions are: 

Spaces, fittings, etc. for the crew's accommodation are 
completely regulated by the Ships* Security Law of the 
Japanese Government 

Ammonia is permitted and widely used as the refrigerant 
for the cooling coils in the fish hold, and the piping 
materials, scantlings, etc. are also regulated by the same 
law. Brine circulation is not so common 

The ammonia compressor is in the engine room to 
economize space and it is permitted 

Low-speed engines are considered better for frequent 
changes of speed during fishing operations, 

There are no longliners equipped with air-blast in refrigera- 
tion holds or in freezing rooms because of the limited 
space where big quantity of the catch to be frozen at one 
time. Therefore, semi-air blast is more suitable for 
longliners 

MR. J-M. CLAVEAU (France): French shipowners consider 
the cost and maintenance expenses of tuna clippers using 
live bait too high; they are greatly interested in the method of 
fishing tropical tuna fish with longlines as used in Japan. 
They are anxious to know whether the Japanese designers 
would be willing to supply information about their refrigerated 
tuna longliners. The following bask data concerning the use 
of these boats would be of particular interest : 

The size of the crew required for tuna longlining must be 
one of the essential economical factors. It would be 
interesting to have full particulars regarding the manner 
and percentage of the distribution among the shipowners 
and crews of the proceeds from the sates of the fish. 
What approximately are the monthly earnings of a Skipper 
yid a seaman of a tuna longliner in Japan? 

Have the Japanese tuna shipowners experimented with 
die IL& tub method, which aims at reducing the number 



of the crew required for jetting the long&iftes in the water t 
Haw these experiments ptoved satisfactory? 

What, in order of preference, are the live bait species used 
by the Japanese tuna tongtinen? 

What are the species of tuna caught by the high sea 
longliners, and in what percentage? 

What is the approximate sate price of these species in 
Japan? 

MR. Y. KANASASW (Japan): Answering Claveau he gave exr 
amples from a fisheries company where he is the president. 

The distribution of the income among the owners and 
crew is as follows: 

(a) Fishing boat from 300 to 500 GT: 

owner (the income from the sales of the fish- 
expenses) x 65% 

crew (the income from the sales of the fish 
expenses) x 35% 

(b) Fishing boat above 500 GT: 

owner (the income from the sales of the fish- 
expenses) x 70% 

crew (the income from the sales of the fish- 
expenses) x 30% 

(c) The monthly earnings of the captain, skipper and 
seaman are approximately as follows: 

Captain: 61 to 79 (U.S. $170 to 220) 
Skipper: 75 to 93 (U.S. $210 to 260) 
Seaman: 32 to 43 (U.S.I 90 to 120) 

The Japanese tuna shipowners have no experience with 
the U.S. tub method for the baiting 

Hie bait for skipjack or bonito pole and line fishing is 
entirely different from that for tuna longline fishing. 
Live fish bait is used for the former, while the bait used by 
the tuna longliners are frozen saury pikes. Both of these 
baits are easily obtained in the market and it is a waste of 
time for the fishing boats to catch them by themselves 

The species of tuna caught by the deep sea longliners 
are as following: 

Stiff price per 

Species Percentage 2,240 /Ml. 000 *j.) 

Yellow fin tuna 50% 286 to 125 

(U.S. $800 to 9 10) 
Big eyed tuna 5% 239 to 286 

(U.S. $670 to 800) 
Albacore 5% 304 to 429 

(U.S. $850 to 1,200) 
Striped marine 10% 257 to 314 

(U.S. $720 to 880) 
Black marine 20% 904 to 378 

(U.S. $850 to 1,060) 
White marine 5% 268 to 304 

(U.S. $750 to 850) 
Broadbill sword fish 2 % 378 to 572 

(U.S.$ 1.060 to 1,600) 
Others 3% 143 to 239 

(U.S. $400 to 670) 



MR. H. KJUSTJONSSON (FAG): At the first Fishing Boat 
Congress the U.S. pole and line tuna fishing boats were 
described in detail and the Japanese bonito boats are des- 
cribed now. There are. however, at least two other typea of 
pole fishing boats that have not been described yet in these 
two Boat Congresses: one is the rather simple type bonfco 



FISHING BO At S OF THB WORLD : 2 TACTICS 



boat used in Cuba. H* other development in recent years, 
morty since the first Boat Congress, is the creation of a pole 
and Hne tuna fishery out of Dakar, where nearly 100 tuna 
dippers operate now. These boats resemble the American 
tuna dippers, but there are some significant modifications; 
the bait tanks, for instance, ate not on deck but flush in the 
hull. He hoped that someone from France would give a 
description of these boats. 

MR. J-M. CLAVBAU (France): Three types of French tuna 

vessels are preeeatiy in use: 

+ The 65 lo 82 ft. (20 to 25 m.) wooden trawler-tuna 
dipper, engaged in albacore fishing from June to Novem- 
her off tiie coast of France, and in trawling from Decem- 
ber to lime 

The 72 to 85 ft. (22 to 26 m.) baby tuna clipper, equipped 
with a 300 to 350 h.p. motor and two auxiliary 20 h.p. 
motors for driving the pumps of the 4 bait wells. The 
profile is similar to that of the CaUfornian tuna dipper. 
It has 4 fish-welb with a total capacity of 6,750 to 
1 1,200 Imp. Gal. (30,000 to 50,000 1.) of water for keeping 
tile live bait. It has no freezing apparatus, but only 
low-powered refrigerator for storing at 32 to 28F 
(0 to 2Q tuna in ice, so that it can land 20 to 30 tons 
of tuna fish. This type is used in the summer tuna 
fishing season off the coasts of France, and then in the 
six-month yettowfin tuna season off the coasts of West 
Africa. It is manned by a crew of 13 to 15 men 

Freezer tuna clipper. This is a steel ship of very recent 
construction in France: 2 series axe now in use: 

(a) The 89 ft. (27m.) clipper, equipped with a 400 h.p. 
motor and two auxiliary 60 h.p. motors for driving the 
pumps to the 6 bait wells and with ammonia refrigera- 
tion compressors at 100,000 BTU (25,000 kcal.). Its 
general profile is that of the CaUfornian tuna clippers, 
but it differs from the latter by reason of smaller super- 
structures and the considerably reduced volume of the 
bait tanks situated on the deck. This ship is equipped 
with small fishing racks in the calm waters off the coast 
of Africa. It has no dry fish hold, all its tanks being used 
first for storing the live bait and then for freezing the 
tuna in brine and storing it. It can land about 35 tons 
of tuna fish. This type of ship is essentially intended for 
fishing tropical tuna off the coasts of Africa, where it can 
navigate the whole year round. It is manned by a crew 
of 15 men 

(b) Hie 118 ft (36 m.) clipper, equipped with a 
600 h.p. motor and 2 auxiliary 120 h.p. motors. It has 



Its profile and deck equipment are similar to those qjfthe 
previous ship. Its wider cruising range allows it to 
remain at sea for 1 month and to land about 150 tons 
of frozen tuna fish. It is manned by a crew of 17 men 
and is used for fishing tropical tuna 

Mm. J-O. TIIAUNO (FAQ): The French use longer poles 
than the CaKforaians, and have a line and a number of 
tackles from a wife between the masts to help to take the 
fish on board. It would be useful to know the ma^ considera- 
tion beteid the fishing techniques. 

Ma. E Rms RJSOTD (Cuba): Cuba has kept to traditional 
fishing jear and methods. Both conduction and types of 
boats are rather antiquated; there is haitUy any dtffcraice 



between the boats that were built on the island at the and of 
the last century and today's boats. This situation is due to 
the lack of specialized technicians such as draughtsmen, 
fishing boat builders etc. Recently the visit of an FAO 
fisheries economist stimulated interest in the modernization 
of the fishing fleet, or more exactly, its creation, because the 
present fleet cannot be modernized or even unproved. 

There are two main types of fishing boats: the bonito boats, 
which measure from 40 to 70 ft. (12.2 to 21.3 m.) LOA, and 
the lobster boats, 30 to 40 ft. (9.15 to 12.2 m.) long* They are 
both made of wood and am mostly of the schooner type with 
sail propulsion; recently they have been motorized, thus 
converting them into sailing vessels with auxiliary engines. 

Their layout is not functional: 2 or 3 of the 7 crew members 
can sleep in the forecastle on the lobster boats, though not very 
comfortably. This compartment has littte depth as the boat 
has a very low freeboard. Aft of this compartment is the fish 
hold that will take 20,000 to 30,000 Ib. (9 to 13.5 tons) of fish 
with ice. Next comes the live well, in which the live bait 
("majtia" variety of sardine) is kept. This well is a tank 
with several orifices to allow the seawater to enter through 
pipes. A slow-going boat and a tank with small orifices will 
not allow free circulation nor proper oxygenation of the 
seawater, and consequently the "majua" bait can be kept 
alive for 24 or 48 hours at the very most. Towards the stern 
there is another small compartment, just as inconvenient as 
the first, where the rest of the crew steeps. 

The motorized boats have their engines placed between the 
live well and the stern cabin. The drinking water is kept in 
barrels on deck; a small charcoal stove serves for cooking; 
a small canvas shields from the sun both the fish lying on 
deck and the men while they fish and clean their catch. The 
compass and helm are also under the canvas. 

Bonito are fished with rod and live bait. Cuban fishermen 
are undeniable highly skilled in this type of fishing. 

The boats used for catching spiny lobsters are smaller, 
shorter and have no normal fish hold. There is a live well in 
the centre of the boats, similar to that used by the bonito 
boats for live bait, in which the lobster are put. The live 
wells will hold 300 to 600 Ib. (135 to 270 kg.) of lobster. 
The gear used is the "chapingorro", namely a rod, that 
together with a glass-bottomed bucket, can be used to fish 
at depths of not more than 6 fm. 

In Cuban bonito and lobster boats, the longitudinal lines 
are very curved at the stern; consequently the boats are slow. 
There is considerable suction resistance due to these lines, but 
the boats have inherent stability since a large part of the 
total displacement lies low. The frames, keel, stem and 
clamp and structural parts are extremely thick, and the 
timbers used are heavier than water. In addition, the boats 
haw a wide beam, approximately a third of their length, 
which contributes still further to their stability. 

Being unacquainted with Ike principles of hydrodynamics* 
the skippers and owners use too much power. In most 
cases, with half to one third of the power, the boats would 
sail at the same speed and consume much less ftiel. In addition, 
there to incorrect choke of propeller revolutions, that is too 
Mghr.p.m. Further, the owoinsuUpropeik of too large 
diameter, and as a result a proper pitch-diameter ratio is by 
no moans attained. 

Obviously til this is doe to ignorance. Some tin ago when 
inspecting latmches of the Navy in various fishing ports of the 
island, he was abie to see the defects noted above. He forth- 
with became very 



NON-TRAWLING FISHING METHODS DISCUSSION 




Fig. 88. Lines of Spanish tuna bait fishing vessel 



for modern skippers and suitable for the Cuban coasts, and 
for that purpose he studied the FAO projects and publica- 
tions. Further, on several occasions he got the skippers and 
fishermen together, and boarded their boats with them to 
learn at dose hand their shipboard needs. In this way he was 
able to analyse and ascertain what would be the most suitable 
type of boat for the kind of fishing practised in Cuba. There 
is a great interest among most Cuban shipowners and fisher- 
men with regard to creating a new fishing fleet suitable for 
their coasts, which are fairly broken and where allowance 
must always be made for the shallow draught. 

MR. H. R. BULLIS (U.S.A.): An article on the Cuban tuna 
fisheries published in the "Commercial Fisherman's Review" 
five years ago gave the sizes of vessels, number of crew and 
the fishing technique. The vessels fish for their own bait 
using a beach-seine. 

MR. V. ESTBVB (Spain): One very typical fishing boat on the 
northern coast of Spain is that from which bonito is fished 
with rods. These small boats, 59 to 72 ft. (18 to 22 m.) in 
length, are made of various timbers; the keel, the stern, the 
stern post and the frames are made of oak, the keelson of 
eucalyptus and the rest of the hull of pine. These are strong, 
seaworthy boats, very good for navigating in the Atlantic and 
die Bay of Biscay. Lines and general arrangement is shown in 
fig, 88 and 89. 

The propulsion equipment generally consists of a diesel 
engine of ftom 150 to 250 h.p. at 300 to 600 r.p.m,, coupled 
by a dutch to a fixed-blade propeller. The engine room is 
usually located to die centre of the boat in order to give good 
trim under any possibk load. Usually the auxiliary machinery 
consists of two sets of mechanical pumps of from 20 to 30 h.p. 
tit circulate wafrr through the live bait tanks. Bitter of 
time pumps can take care of all these tanks whfle the other 
is out of use. In addition, each set works another pump of 
gitfcter dachas pmrara, that produces artificial rain to 
attract the fish, imd is also used as a fire extinguisher. One 



of these sets has an air compressor to start the propulsion 
motor and the other a dynamo of about 5 kW to provide 
electric current when the boat is in pent. When the boat is 
at sea, electric power is supplied by a dynamo coupled to 
the shaft. 

The compartments in the hull are as follows: the chain 
locker; the forecastle that will hold 10 to 12 fishermen; an 
insulated fish hold; the engine room with live bait tanks, one 
toward the bow and one toward the stem, and with fuel tanks 
on the sides; a room for the two enginemen and finally a 
storeroom for fishing gear. 

The front bulkhead of the engine-room and the wheel- 
house are usually made of steel plates and the galley and food 
stores are located in the superstructure. The holds are 
insulated mainly with sheets of pressed cork, glass fibre or 
asphalt products. The insulation material is covered with 
an inside planking of wood over which cement mortar is 
applied. 

The live bait tanks are made of sheets of galvanized steel 
or else an aluminium alloy resistant to aeawater corrosion. 
Salt water is introduced into these tanks through pumps 
from the auxiliary units, and passes out through the dis- 
charge funnels on the top portion of the tanks, thus producing 
the continuous circulation of seawater necessary to keep the 
bait alive. The inside of these tanks is properly lighted. 
These boats usually have three wood or steel masts with 
booms. 



MR. J. TYRRELL (Ireland): In Ireland they are not concerned 
with drift-net fishing, which has, with few exceptions, been 
discontinued for many years, due to uncertainty of catches 
aad expense of gear. They have therefore developed multi- 
purpose vessels in sizes from 50 to 80 ft. (15 to 25 m.), for 
operating herring ring net, otter trawl, Danish seioe and lately 
the floating trawl The chfef fishing methods have been 
bottom trawling and Danish seining, for which the indi- 
vidual catches were relatively small. 



BOATS OP THE WORLD : 2 - TACTICS 



rftatoraaltoy^withcabta,engii>e- H noto * the ? d ?ff!!!!,' 

S^n^Sned Danish seine- interest, since his company 



aft, and a combined Danish setoe- 
has been found satisfactory for 
. Modem gear development,, particularly 
ring net and the mid-water trawl, have, , howevw, 

adnfc* Ugto of 



^ 



development, an improved deck arrangement is clearly 

becoming necessary. 



uwMe of thto tayout has yet * , 
made designs and model, which are presently being discussed 

. (23 m.) long with 20 ft. (6 m > 
accommodated forward, followd by the 






1100] 



NON-TRAWLING FISHING METHODS DISCUSSION 



engine room and the fish hold aft* The wheelhouse would be 
located forward of amidships, with the winch, of the combined 
Danish seine and trawl type, at about mid-length. 

A transom stem seems most desirable for this layout, and 
care must be taken to preserve trim, with a heavy load located 
considerably aft of midships. 

The chief objections are : 

The crew dislike living forward 

The engine installation requires a relatively long shaft 
running below the fish hold 

The crew are doubtful about the safety of working on a 
wide exposed aft deck 

He felt these objections could be overcome without much 
trouble, except possibly the first, which goes against all 
traditional practice. He should like to hear from Hanson or 
Kristjonsson whether they have met with similar difficulties 
with vessels of the proposed arrangement, and how these 
were overcome. 

MR. H. C. HANSON (U.S.A.): He had witnessed a fast transi- 
tion in fishing boat types in the Western U.S.A. and in 
Alaska. The first step from the rowing boat came with the 
bow-pickers, with the engine aft. The West Coast was at that 
time a new country without heritage or tradition, and con- 
sequently with little prejudice, which meant quick changes. 
Purse seining started about 1914 and brought about the 
change from bow fishing to stern fishing. The boats developed 
from the flat bottomed seine boats and the trolling vessels to 
the combination boat as it is known now. Seine fishing, trol- 
ling, lining and trawling are all done by these boats developed 
within the last 20 years. Large tuna vessels often operate for 
up to three months at sea. 

Practically all vessels on the West Coast are now fishing over 
the stern. Tuna vessels are being stripped of their bait tanks 
and are converted to purse seining. A net table is still used 
in combination with the powered block. 

He expected that in the near future West Coast fishermen 
would go further out to sea, and it might well be that they will 
then adopt smaller types of stern trawlers, such as are now 
operating in the North Atlantic. 

MR. D. L. AtVBRSON (U.S.A.): According to Hanson, the 
change-over to multi-purpose fishing boats has come about in 
a short time, and this has been advantageous to the fishing 
industry. Up to now fishing has been done close inshore and 
the methods used have been trawling and purse seining. 
In future, fishing for extended periods might be done in 
distant waters like the Gulf of Alaska and the Bering Sea, 
and a new type of vessel may be considered. 

Regarding the change* in the tuna fleets, there has been a 
tendency in recent years to remove the bait tanks and equip 
the vessels for purse seining. This change has been mainly 
due to the distribution and schooling patterns of tuna, which 
make it more profitable to catch them with a purse seine. 
The introduction of nylon nets has made it possible to use 

Regarding changes in deck arrangement of small gillnet 



vessels, ahiminium construction has been indicated. One of 
the advantages of this material is the lighter weight of the 
vessel and the consequently greater payioad. 

MR. H. KJUSTJONSSON (FAO): When he was as a young 
student on the U.S. West coast during World War H, fee frt 
for the first time acquainted with the Pacific type boats with 
the wheeihouae forward. He had, as a youngster, worked on 
the Scandinavian boats in Iceland and it was immediately 
obvious to him that the Pacific type had many important 
advantages, for instance, in regard to purse seining. He had, 
however, the same misgivings about their seaworthiness as- 
expressed by Tyrrell. To test their performance in rough 
weather, he worked his way to Alaska, mainly with the objec- 
tive of testing the performance of this boat type under rough 
weather conditions somewhat similar to those in the North 
Atlantic. He returned to Seattle on a 78 ft. (23.8 m.) puree 
seiner, an 11 days' voyage, and, luckily for him, they got a 
full gale in the Gulf of Alaska lasting for two days. After this 
he was quite confident that he could recommend thpTodaiKhro 
to test this type. He wrote an article in an Icelandic news- 
paper which came at the right moment. The people at home 
were optimistic and asked him to go ahead and have a boat 
built of the new type to be tested in Iceland. The Icelandic 
Skippers* Union sent over on experienced purse seine skipper 
who familiarized himself with the Pacific purse seining gear 
and method and sailed the boat home. Unfortunately this- 
boat, an 84 ft. (25.6 m.) purse seiner, came a little bit too late 
to Iceland due to late delivery and missed the herring season in 
1945. This meant that this design had not been tested when a 
big-scale rebuilding of the boats was decided immediately 
after the war, mainly in Sweden. This Pacific type boat has 
been operating in Icelandic waters since 1945. It has been 
found to be eminently seaworthy. As a matter of fact, it & 
used during most winter seasons to aid the cod fishing boate 
and to tow them in when they have engine trouble. That m 
not necessarily because it is the best aad most seaworthy 
boat, but it is seaworthy enough for this tough service. Thm 
is still a prejudice against using it for any fishing method where 
the gear is handled forward of amidships because of i 



or real difficulties which are anticipated due to windage on the 
wheelhouse, lack of deck space forward etc. This has however 
not been tested in Iceland yet after all these years, and this in 
spite of the fact that such boats are used successfully in the 
Pacific halibut longlinc fishery in the stormy Gulf of Alaska. 

MR. J. VENUS (U.K.): His firm had built orthodox trawlers 
for middle distance trawling. The efficiency of the design had 
not been questioned. However, accommodating the crow 
forward may have an adverse effect on the willingness of the 
crew to go to sea, because of the heavy motion in high seas. 

MR. H. C HANSON (U.S.A.): As regards living quarters for- 
ward on the combination type boat, this seems to bo all right 
as 95 per cent, of the owners prefer it this way. Hie only 
difficulty is probably .the over-icing occurring in the North 
Atlantic, but there is also risk for king in the Pacific and no- 
difficulties seem to arise. 



[101] 



TRAWLING: DECK DESIGN AND EQUIPMENT 

by 
A. VON BRANDT and C. BIRKHOFF 

In several countries, such as Belgium, United Kingdom, Federal Republic of Germany, France, 75 to 100 per cent, of all landings 
from the aea aw obtained by trawls. The trawl thus is an important gear to gather the protein resources of the sea. 

Its development is closely connected with the fishing vessels which represent approximately 80 per cent of the capital invested in 
flff*rrH- The efforts to catch more with larger nets, to extend operations into deeper waters, and to reduce manual work by mechanization 
requires a corresponding development of trawlers with the necessary deck equipment. The investment is considerable in the moat modern 

The beam trawl h the most primitive type used in power trawling. Unless very large, it is light and handy and needs relatively link 
special deck equipment. Its height and width are limited by the beam, 

The introduction of otter boards decisively influenced devk>pmeaU and extended the i^ Winches were needed for the 

longer and stronger warps as well as the gallows to lower and haul the boards. 

The methods of to wing, handling the net and hauling the catch distinguish a "tide trawler* 4 from a "stern trawler", the latter with 
or without a ramp. 

Although the Hem trawler has certain advantages in handling the trawl, side trawlers are still dominating in the North Atlantic. 
On stern trawlers without a lamp the net is hankd over a broad stem toller; the codend with the catch, however, must be hauled over the 
vessel's side, and this takes time. The arrangement of the deck machinery varies greatly, because trawlers are often also used for other fishing 



The stern trawkr with a ramp developed from the desire to process the fish on board, in order to extend the fishing trips. It is 
important that the sailing tkne to and from the fishing grounds and the stay in port be as short as possible so that actual fishing days can be 
the maximum. This also apphes to the time to shoot and haul the nets. Stern trawlers with a ramp have a number of advantages over other 
types. These include the time saved in handling die trawl and catch, thus preserving the quality of the fish, less damage to the nets, better 
working conditions for the crew, a more seaworthy vessel, easier conversion to other types of gear, as for instance pelagic trawls, and more 
favourabk use of the space on board. 

Two-vessel trawling can lead to greater yields than when each vessel operates by herself, and two small vessels can use a larger net . 

Magic trawling has mainly been done with two boats, brt the size of the vessels is limited and fi 

at night Therefore worf is being carried out to develop a pelagic one-boat trawkr. The stern trawkr appears to be the better type of vessel 
for tto operation, 

EQUIPEMENT DE PONT POUR LE CHALUTAOE 

Dans plusieurs pays, tels que la Betgique, k Royaume-Uni, la Republique federak alkmande et la France, 75 & 100 pour cent de 
toutes ks quantites debarquees d'onginc marine sont peches an chalut. Le chalut est done un engin important pour recoltcr ks ressources 
protciques de k mer* 

Son developpement est en relation etroite avec ks bateaux de peche qui repretcntent approximativement 80 pour cent du capital 
invest* dans ks peches. Les efforts pour pecher phis avec deplwgraids wets, pour eteiita 

t pour redirire k travail manud par la mecsiusation nfaessttent un developpement correspondant des chalutien poss6dant requipement de 
pont necessaire. L'investisscment est considerabk dans ks stades ks phis recents du developpement. 

Le chalut * perche est k type k plus primitif utilise dans k chalutage avec des bateaux mecanises. A moms qu'ill soit tres grand, 
ilcstlegCTetmanoeuvTahketnicessitere^ Sa hauteur et sa iargeur sont Iimitecs par la perche. 

L'introduction des plateaux de chalut a exerce* une influence decisive sur ks devetoppements et a augment* la portee de la peche. 
fiafaOudesttttiuXdesfunespiw plateaux. Les methodes 

de mnorquage, de manoeuvre du fikt et d'embarquement de la peche distinguent k "chalutage sur k cote"* du "chalutage par Tamere", ce 
dernier etant pratique avec ou sans rampe. 

LeschaItitiBi$i>echantsiirle4fo 

certain! avantages dans la manoeuvre du chalut Sur ks chalutien sans rampe, k fikt est hisaft a bord sur un large rouleau place 4 1'arriere ; 
k cul-de-<diahrt reafermarrt te* p^ La disposition de 

de pont varie beaucoup parce que ks chalutiers sont souvent utilises pour d'auttes methooes de ] * " 



L*kle>duchahitkrnmnid f une rampe piwientdud^ 
est impor^qik temps pass* potato 

dep^chertelkpu&seetre maximum. LeschahitkfiptehttitparfaiTlitee v nii^ 
nippct anx 

du poi^; n^ i<^ unimdikwi twue Jt 

' 



k mer do navto ; pte de ftdMtes pow 

et w^ utilisation pMft favorabk de Teapaee 4 bord* 

Le^autagei deux navires peut donner des naidenmnte phis ekves que lorsque cheque navfae opere seul, et deux petits navires 
peuvent utihser un pnts grand fflet* 



Ta^eiepaii^ 



Ledialatier^Mu^iitjrTa^eiepaii^ 
k meilleur pour cette openuon. 

EQU1PO PARA LA CUBIERTA DG LOS ARRASTEROS 



w captm con artts tie amwtre. Q te de urattn cowtftuye. POM. on Jmporttrte mlo p*n moffer lot 
oe pnxeinas oei mar* 

f!02] 



FISHING METHODS AND DECK ARRANGEMENT TRAWLING 

Sunerfeocic4iainicinto et$6 ettrechainente relacionado con el dc lot barcoi de peaca, QUO rtfunetentan, aprox.. tl 80 pof cjenfto dot 
capital invertJdo en to indurtria petquenu Lot eafaenBOt encaminadot & peicar mis con redes nayoraa, A rMiMrtfc la -peaca a agua* info 
pfpfiindai y t rpdudr el trabajo manual mediante it Tnamnhractop, cxisea mcjorai oorrfapofHttentei en lot airattrqx* y en el material de 
oibierta neceaario, En U fa*e mfc nxxtenm de perteckraan^ 

El art* de vara e d tipo mat primitive) crapioaxk) en la pc^ de am^tre con buxni meciiikx^ A roeoot qoe tea muy grande, e* 
Ugero, maniobrtWe y necearita relativamente poco equipo de cubfcrta etpedal. Su altura y su anchuxa estan Hmttada* por la vat*. 

Ui introducddn de IM poeita ... 



poeita* 
neoctitarqn maqiiinillat para lot cabtoi de 



de manera dediiva en el perfocckmamierito y penniti6 ampliar el akanoe de la 
tie mat pesados, ati como pescantet para izar y arriar las puertas. 



En lot metodot de arrastte, de maniobrar el arte y de embarcar la captura ae diitinguen el arrattre por el coatado y el arraitre por 
la popa; eite liltimo con ramp* o tin elUu 



varia mudio porque lot arraitroroc ae suekn emplear 
U idea eWarrastrero con " ' 



Es important* redudr en todo k> posibfe la durad6n de lot viajes de ida y vuelta a lot caladerot y la pcrmancncia en puerto, a fin de que el 
niimero de dias habfles de petca sea el maximo. Etto es tambien de apficad6n al tiempo dedicado a largar y virar el arte. Los arrastren* 
con ramp* a popa tienen varias ventajas sobre tot otrc* tipcra ,entre las que ettan el tiempo abom^ 

de la capture, que contribuyen a mantener la calidad del pescado, perjudican menos a las redes, la tripulaci6n trabaja en mejorat coodickHies, 
el barco ttene mas resisteacia a lot efectos del tiempo, es mas facil convertirk) para emplear otras dases de arte y el espacio a bordo etta 
dittribuido mas favorablemente. 

La petca al arrattre con dos barcos puede producir mayores rendimientos que cuando cada barco opera por si solo, y dot barcos. 
pequeflot pueden emplear un arte grande. 

El arrattre pela^co se ha efectuado prindpalmente con parejas, pero el tamaflo de los barcos es limitado y la pesca resulta dif idl en 
mar gruesa y de nocne. For estas razones se ettudia la manera de perfeocionar un arte pelagkx> para una sola embarcacion. El arrastrerc- 
que pesca por la popa parece ser el mejor para etta operaci6n. 



THE trawl, the most important gear for demersal 
fish in sea fisheries, is used at all fishing depths, 
from the shallow off-shore waters to the deepest 
fishing grounds known today. Although trawls have been 
used since the invention of nets, they have only attained 
their present importance in recent times. This im- 
portance depends on, and has grown with, the develop- 
ment of suitable vessels, their propulsion and deck 
equipment. Fig. 90 and table 19 show the magnitude of 
trawling compared with other fishing methods. 

The trawls were developed to: 

Catch more fish by increasing the volume and 
efficiency of the fishing gear 

Fish in deeper waters off shore 

Reduce manual work by mechanization 
Be suitable for many species of fish 

Catch fish not only on the bottom but also in mid- 
water 

Be suitable for bad weather operations 

Fish and other marine animals must be in certain con- 
centrations to be trawled. If not, such gear as hand lines, 
longlines, fixed bottom set gillnets, trammel nets or traps 
are used. The encircling net only, in size of catch, can be 
compared with the trawl, although the encircling net is 
only used for pelagic fishing. 

The trawl plays little part in inland water fisheries 
although smaller types of trawl are still used in some lakes 
and rivers, such as the large lakes of South-east Europe, 
the Caspian Sea and the large African lakes. 

The trawl it closely correlated to the vessel in which it 
is used, and no other gear has had such a great influence 
on the design of fishing vessels. 

The development of fishing vessels from the open 
rowing boat to the factory ship has been accompanied by 



the development of larger nets requiring greater towing 
power; thus the development of the trawl is closely 
connected with that of propulsive power. The influence 
of the net was apparent in the sailing trawlers which had 
to be fitted with special sails to increase their towing 
power. With the development of special vessels and deck 
equipment, trawling has become a fishing method calling 
for considerable capital investment. Consequently, it is- 
changing from a single owner and small business basifr 
into a large enterprise. Although the trawl requires a 
smaller crew and less working time than several other 
methods used for bottom fish, the total expenditure for 
the equipment is high and continues to increase. 



TABLE 19 
Bottom tfawi catches exfWMPid M 



ofttototftl 



Belgium 
England 
Germany (Federal Repul 
France* 
Iceland 
Canada: Atlantic coastf 
Pacific coast 
Phillipines . 
Portugal 
Scotland 
Union of South Africa (i 
U.SA4 
Japan 
Norway 


t>lk) 
Kclud 


ingS< 


>uth> 


VesU 


Urka) 



100 
91 
91 
T* 
61 
42 

5 
39 
35 
35 
32 
25 
22 

4 



12 



*Data for 1955 
fBy trawlers under 70 1 
Bytrawienover90ftLOA 30 

^% 
tData for 1949 



[103] 



FISHING BOATS OF THE WORLD : 2 TACTICS 




fig. 90, Contribution of bottom trawl catches to total catches in the 
North Atlantic area 



GENERAL DESCRIPTION OF FISHING GEAR 

Net 

The size and design of the trawl is governed by the species 
to be caught, and by the available towing power. Until 
recently, ideas about the behaviour of the trawl nets in 
action were only hypothetical, but nowadays direct or 
indirect underwater observations have made it possible 
to understand better how the net behaves in action and to 
determine its relation to the vessel. 



Various designs have been evolved to achieve good 
filtration of water and to avoid a swirl before the net 
which would repel the entering fish. The material, com- 
position and shape of the parts, mesh size, etc,, of the net 
scarcely influence deck equipment and need not be 
mentioned. 



Accessories 

Fig. 91 and 92 give examples of modern trawl designs, 
which are no longer simple net bags but include acces- 
sories that are of essential, if not decisive, importance for 
obtaining good catches. The largest possible width and/ 
or height of the net opening is essential for effective 
operation. When the net is towed by one vessel, the 
horizontal width can be obtained with booms or beams 
or oner boards. Booms were first used by sailing boats, 
as shown in fig. 93. It is much easier to get the desired 
width of opening by towing with two boats. Two-boat 
trawling, therefore, is widely practised. Vertical spread 
is partly achieved with net floats or sheering equipment 
or kites, and partly by design. 

The size of the net and the opening is also influenced 
by the length of the lines (groundrope and headline). To 
ensure smooth running of the groundrope over a rough 
bottom, wooden bobbins and hollow iron balls weighing, 
in total, as much as 1.5 tons are attached to the rope. 
Handling calls for special deck equipment. 



Handling of fishing gear 

The time taken for one haul depends on the bottom and 
on the abundance of the fish and may vary from a few 
minutes to several hours. The trawling speed depends on 
the net type and species of fish to be caught. Large 
trawlers work at 3 to 5 knots for most species of fish. 
Small vessels, however, fish at lower speeds. Low speeds 
are especially important in trawling for some flat fish. 

Shooting and hauling require special equipment, par- 
ticularly for handling the lines and accessory gear. It is 
important to bring the codend on deck without damaging 
the fish. 




flf. 91. Modern Enftttk bottom mw/(Gtanw, 1936) 
1104] 



FISHING METHODS AND DECK ARRANGEMENT TRAWLING 




. 92. Modern German round-fish trawl (ScMtrfe, 1957) 



BOTTOM TRAWUNG WITH ONE BOAT 
General description 

To keep the trawl open horizontally from only one boat, 
booms are attached to the bow and stern to which the 
warps are fastened, as shown in fig. 93. This method, 
however, was mainly developed for sailing boats, and has 
been practised since ancient times in Europe and in Asia. 
Another well-known method is to open the trawl hori- 
zontally with a stick or beam and to trawl with one warp 
and bridles as shown in fig. 94 (beam trawl). With the 
low towing power of sailing boats, small trawls can only 
be used and they are lowered and hauled by hand. 

The width of the net opening of the beam trawl is 
determined by the length of the beam, which varies 
from 25 to 45 ft. (8 to 14 m.), and sometimes skids 
attached to each end of the beam hold the mouth 
vertically. The beam and skids give the opening a certain 
rigidity. In large sizes, however, the long and heavy beam 
makes it much more wieldy than the otter trawl (Morgan, 
1956). It is really a gear for small inshore fishing craft 



and is used in European, Asiatic, African and American 
coastal waters. 

Otter boards were first used at the end of the last 
century, although the idea is old. Line fishermen used 
and still use a similar device to control the direction of 
lines in running water or when towing from a boat 

The otter board for trawlers was used in Ireland about 
1870 but was first reported from England. Originally the 
otter trawl, like the beam trawl, was towed with one warp 
and bridles but a second warp was soon added. The 
introduction of otter boards encouraged the manufacture 
of larger nets for use at greater depths. Fig. 95 shows 
such a German trawl. Concurrently with the develop- 
ment of larger trawls, more powerful vessels were 
designed (fig. 96), which extended the fishing time and 
distance from home ports. Longer and stronger warps 
led to powered winches, and the invention of the gallows 
enabled the boards to be handled. 

Methods of trawling and handling the net determine 
whether the vessel is a "side trawler" or a "stern trawler*'. 




Ft?. 93. TowiHtbyaboatsallinf athwart t the horizo*toJope*tnf of the i 

qft of the boat 

[105] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



In the first type, the two warps run asymmetrically 
because the net is shot and hauled oa one side. In the 
item trawler, however, the warps run symmetrically. 
The codend is hauled over one side of the vessel or over 
the stern. 




Fig. 94. Japanese beam trawk 



11 to 14 mm can work simultaneously when unloading. 
The superstructure is located aft of the hatches. 

As only one side, generally the starboard, is required 
for handling the net, the portsidc superstructure on 
modern vessels is usually closed. A working passage runs 
to starboard, and this also accommodates the bulky 
bobbins of the ground rope. Arranged on the free 
working deck forward of the superstructure are the fish 
ponds, where the catch is gutted, washed and sorted. 



STERN TRAWLER WITHOUT A RAMP 

Origin 

This type of vessel was developed in fair weather regions, 
such as the Pacific coast of U.S.A. and in the Mediter- 
ranean, and has only come into use as a near-distance 
trawler in recent years. In order to utilize drifters, 



SIDE TRAWLER 
Origin 

The side trawler is the most familiar type of vessel in the 
North Atlantic deep sea fishing industry and it has been 
developed over a longer period than other types. In the 
days of sailing trawlers, the trawl was handled on one 
side, and this arrangement was inherited by mechanized 
vessels. Indeed, modern side trawlers still make use of the 
wind, heaving to so that the net can be shot and hauled 
from the weathersidc to prevent the vessel being driven 
over it, and to help stream it out 



The equipment of side trawlers has become more or less 
standardized internationally. There are two gallows for 
the otter boards and a derrick for the bobbin wire in 
front of the after gaUow. There is also a derrick at the 
foremast for shooting and there may be a third derrick 
near the mast. Between the hatches and the deckhouse 
there is a winch from which the warps run forward and are 
guided over the centre and wing bollards to the gallows. 
Aft at the bulwark there is a messenger, with sheave and 
slip hook or slip block (also called a towing block) or 
other equipment for connecting the two warps when 
fishing. Quarter rope- and bridge tackle-sheaves at the 
deckhouse haul the net, and the tackle at the foremast 
lifts the filled codend on deck, as shown in fig. 97. 
Sometimes, on smaller inshore trawlers, the winch is 
placed before the hatches, <MT between two hatches. This 
requires corresponding fairkad bollards. 

The fish hold is normally in front of the engine room 
which is in the aft part erf the vessel. The crew's quarters 
today are usually located near the messrooms aft, to 
avoid unnecessary walking over the open deck. The 
trawlers have a forecastle to improve seaworthiness and 
to protect the crew working on the open forcdeck where 
working rooms and net and cable rooms are located. 

Trawlers have hatches over the fish holds and these are 
arranged at regular distances, so that several groups of 




Fig. 95. Development of the German herring bottom trawl 
(van Brandt, 1957) 



seiners, longliners, tuna dippers and, possibly, trollers, 
throughout the year, it was necessary to equip them for 
an alternative fishing method, such as trawling. And as 
the other fishing gear with the exception of most of the 
drift-netswas handled over the stem, it followed that 
the trawl was also handled over the stem. The gallows 



M06] 



FISHING METHODS AND DECK ARRANGEMENT - TRAWLING 



1800 



i860 



STVAfi 



1902 






STEAM 





ff. 




' oftk* European trawler (compare alto fig- 2) 
[107] 



FISHING BOATS OF THE WORLD : 2 TACTICS 




Fig. 97. Deck arrangement and leading of warps on fide trawlers 



were symmetrically arranged at the sides near the stern. 
A stern-roller is often used for shooting and hauling the 
trawl, and the catch is sometimes hauled over the side 
as the existing derrick can best be used as the "cod- 
end derrick*', while the heavy tackle at the mast serves 
as the "fish tackle". 

The deck equipment of these vessels varies, often 
depending on the original fishing method, and even the 
most modern vessels remain typical of their original 
character. 



Hie vessels have two movable side-gallows, either 
reversed U-shaped or davit, situated approximately 
10 to 16 ft. (3 to 5 m.) forward of the broad stern, which 
is often a transom stern. This latter is best for the large 
net-roller and it provides a good working space for 
shooting and hauling the nets. 

The vessels have a mast, aft of the deckhouse, with a 
large derrick to serve the hold and fishing gear hatches 
and the aft working place. A heavier tackle for hoisting 
the codend over the side is often attached to the middle 



SSKSo* 




of the large derrick. There may be another small derrick 
at the mast for this purpose and also for hoisting the 
lifeboat. 

There are various arrangements of the winch and the 
fairlead bollards, differing in types and sizes from the 
small shallow-water winch with a twin drum, transversely 
set, to the deep-sea winch with two separated drums 
placed in a longitudinal direction. The fairlead bollards 
are arranged according to the working direction, so that 
there are either centre bollards between the gallows or 
two wing bollards. Modern winch drums are aligned 
towards the gallows by using a cardan shaft, and rotatable 
davit-gallows are fitted. Vessels with larger trawl winches 
working in a longitudinal direction sometimes also have 
a small seine-double-capstan or two additional drums 
as shown in fig. 98, which may be advantageous for 
pelagic fishing. This type of vessel is very profitable in 
fair weather areas, as it can be adjusted to the best 
fishing method for existing conditions. With the addition 
of a trawl, such a vessel is capable of working throughout 
the year. As it costs relatively little to build and operate, 
this type of vessel has a great future in fisheries where 
favourable weather prevails. 

STERN TRAWLER WITH A RAMP 
Origin 

The idea of processing fish on board to facilitate voyages 
to remote fishing grounds has led to this type. The pro- 
cessing machinery required a large space, and the shelter 
deck was the obvious place for it. The beam wind 
position on the side trawler when handling the trawl was 
very inconvenient. The height of the shelter deck made 
the handling of the trawl difficult, and heavy rolling had 
to be avoided because of its effects on the processing 
machinery and conveyor belts. The answer to these prob- 
lems was to operate over a stern ramp which, as was 
soon proved, does not impair the quality of the fish. 



> 98* Ztacfc 4P'iwifCfPMMtf ojtd fandinf of wttt'ps on item 
Wtthoitt ntttip 



, . 

At first, there were some difficulties in handling the trawl 
over the item. Additional sweepline-giltons were used 



[108] 



PISHING METHODS AND DECK ARRANGEMENT TRAWLING 



in the British stern trawlers. These drew the sweeplines 
from the trawldoors to the ramp, simultaneously slacking 
the warps. The arrangement of the trawl winch, fairlead 
bollards and gallows has a slight resemblance to that of 
the smaller stern trawlers without a ramp. 

Warp roller tropes type 

A different arrangement was used on German built 
vessels. The large factory trawlers built for Russia 
used warp roller trollies running on rails along the 
stern ramp which, although expensive, can be handled 
quickly. This arrangement has been given up in new 
Russian vessels where use is made of two conventional 
gallows aft on each side of the deck. 



gear in line with the inclination of the ramp. This 
arrangement allows the wet net, with the exception 
of the full codend, to be kept clear of the ramp and thus 
reduces friction. 

Other equipment includes a derrick at the portal- 
gallows for lowering the codend; a bipod mast over the 
loading hatch, designed to allow the codend to be 
emptied without being lifted; coamings and bobbin 
tracks along the deck for safety when the vessel rolls, 
two short lifting lines which make it easy to fasten the 
warps to the otter boards, and two veering lines for the 
heavy bobbin wire. With this method of handling the 
gear, the flush fish hatch with a chute leading into the 
large buffer store should be located just in front of the 




Fig. 99. Deck arrangement and leading of warps on stern trawlers with ramp 



Gallows type 

A relatively simple solution was found for trawlers of 
conventional size and without a raised upper deck. 
Gallows based on the gallow-sheave principle were 
installed near the stern, turned aft, beside the ramp. The 
transom surfaces were bent inward to guide the otter 
boards to the stern with guide bars. Cross-head bows on 
the gallows heads assured a firm three-point position of 
the otter boards flush with the transom. Two rail rollers 
prevented the warps touching the bulwark when hoisting. 
In most cases, the gallows are single portal shaped 
extending over the whole width of the vessel with two 
fixed warp-sheaves (fig. 99). An alternative version of 
this system, which is adopted by one German company, 
is fitted with two movable warp-sheaves. In this case the 
transverse part of the gallow allows for a transverse 
shifting of the warp-sheaves during operation. When 
separate warps or special sweepline-gilsons, slightly 
elongated back strops and pennants (independent piece) 
adjusted to the ramp are used, the net can be handled 
over the stern without transverse or longitudinal mov- 
able warp-sheaves. 



Another typical deck arrangement in these large stern 
trawlers is a hoisting post with the tackle for hoisting the 



ramp as shown in fig. 99. By unloading the catch from 
the codend immediately below deck the fish ponds can be 
installed on the 'tweendeck in front of the gutting places. 
A free deck space over the fish hold and uniformly 
distributed hatches are needed for unloading fresh fish; 
therefore the superstructure is restricted in size. A larger 
superstructure can be accommodated on a factory 
trawler because the frozen fish can be unloaded in con- 
tainers through a central hatch. 

Advantages of stern trawlers with ramps 

The cost of building such a stern trawler is about 10 to 
15 per cent, higher than that of a comparable side 
trawler, but the stern trawler can fish longer, which might 
result in better annual returns. 

Crews quickly adapt themselves to the stern trawler 
and its deck equipment, and the better working conditions 
are appreciated. Thp advantages of the stern trawler can 
be summarized as follows: 

(I) Longer fishing time because there is 

9 No turn round for hauling and shooting. Ship 
need not be laid athwart to sea 

Generally free choice of the direction of hauling, 
independent of current and wind a special 
advantage when fishing on steep banks 



[109] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



Higher hauling speeds are possible than those 
obtained on ride trawlers, because the warp pull 
is in line with the ship 

Mechanical hauling of the net by the trawl winch 
only, instead of pulling by hands as on side 
trawlers 

No necessity to split the codend 

No necessity to lift the codend, which is only 
tilted and emptied 

(2) More successful fishing because there is 

Better manoeuvrability when hauling, shooting 
and towing as the warps leave the stern symmetri- 
cally without influencing the ship motions. 
Therefore fishing on steep banks, especially in 
heavy athwartship seas, is easier than on side 
trawlers 

The possibility of varying the length of towing 
warp to the different depths of sea without 
damaging the warps in the towing block 

No fouling of the gear when shooting as this is 
cleared into the water when the ship is under way 
and an parts are carried away by the flow in the 
proper sequence. Doors immediately start to 
sheer away 

No unequal elongation of trawl-warps due to the 
symmetrical arrangement of bollards (if any) 
and rollers. Therefore control and readjustment 
of length-marks on warps is not necessary. 

(3) More careful handling of the catch due to 

Shorter death-struggle in the codend lengthening 
piece when splitting the catch because the codend 
is brought to the deck in one pull, this not being 
the case on side trawlers (experience proves that 
up to now the quality of the fish has apparently 
been better) 

Smoother unloading of the codend onto the 
gutting deck immediately after hauling (conse- 
quently earlier protection of the catch from heat, 
light and weather) 

The use of processing and stowing conveyor 
belts, thus reducing fish handling to a minimum 

These points give considerably better quality fish 
than is the case with the conventional trawler. At 
the fish market in Bremerhaven only less than } 
per cent, of stern trawler catches have been unfit 
for sale, although mostly the ships had made 
longer trips. 

(4) Mart careful handling of the fishing gear by 

Better guiding of lines 

Few changes in the direction of pull 

Avoiding uneven load on the warps 

Keeping the warps clear of the ship's hull 

(5) Better working conditions for the crew by 

Saving the long, dangerous and heavy work in 
hauling the net 

Reducing the work of handling 

Having the ramp deck especially the trawl 
winch -protected by the superstructure 



The working deck being completely enclosed 

Having the gutting room in the alter part of the 
ship which is not so much affected by pitching as 
the foreship. The same applies for pitching at 
the ramp which is less than at the forward gallow 
of side trawlers 

(6) Adverse weather effects reduced by 

Linear direction of hauling 

The net being handled only by the winch 

Having the ramp deck and the winch protected 

The working deck being completely protected 




Fig. 100. Operation of two-boat trawler f 

(7) Danger of icing up in "black frost" is lessened due 
to higher freeboard (on side trawlers water shipped on the 
open foredeck may not drain away, as freezing ports are 
frozen up). 

(8) More space for processing machines and their 
arrangement in a continuous processing line (e.g. the 
effective long washing machine) is given by 

The long, completely enclosed working deck 

The location of the codend unloading hatch and the 
storing hold hatches at the opposite ends of the 
working deck 

Drawbacks 

There are only a few drawbacks against the above 
advantages 

(1) Methods for dealing with very big catches or 
splitting them are still to be developed. Up to now 



I "0] 



FISHING METHODS AND DECK ARRANGEMENT TRAWLING 



about 25 ton have been handled safely. However, farther 
improvement* aeon possible. 

(2) Codettds and lengthening pieces must be made 
particularly strong by using expensive materials such as 
Perlonetc. Therefore the loss of a net is very expensive. 

(3) Some difficulties arise by using the conventional 
herring trawl with the second kite. Only time and money 
is needed to solve this problem. 

(4) First costs of stern trawlers are higher than those 
of side trawlers, the difference being bigger on small 
trawlers and diminishing with size. At a length of about 
200 ft* (61 m.) LBP, the difference disappears. 

(5) There is a loss of speed of about S per cent, because 
of the broad aft end of the ship with ramp. 



completing the haul, to dose without endangering the 
vessels, as shown in fig. 100, 

Psychological reasons often hamper successful two- 
boat fishing, as captains and crews must be able to work 
in harmony. It is easier to find two equivalent boats, 
than to find two captains who can work in effective 
agreement. 

Pareja trawler 

The Pareja vessels operate a large trawl at slow speed. 
The boat requires an aft platform for the net and a special 
compartment for the lines. A snatch block hanging 
overboard is used on either side of the stern. In addition 
to the centre and wing bollards on the fore deck, the 




Fig. 101. Deck arrangement and leading of warps on Pareja trawlers with pwtectinf rolfa 

the forecastle 



The many more advantages indicate that the stern 
trawler may well have the greater future. The technical 
details given above only indicate present possibilities. 
In the distant future, stern trawling might be further 
developed to operate almost automatically. 



BOTTOM TRAWLING WITH TWO BOATS 

Two boats can be used to spread a trawl horizontally, 
as in the Spanish "Pareja", the Japanese "Teguri", the 
Italian "Paranzella", and the German "Tuckzeesen" 
fisheries. 



Two small vessels with low engine power are able to tow 
relatively large trawls, no otter boards being required. 
As vessels and warps are remote from the entering fish, 
the catches are larger sometimes twice as large as 
those caught by the one-boat net; so it might be profit- 
able to use two vessels with two crews. This applies in 
theParcjaflshcryforvessebofupto400GT. 

Thwe are, however, disadvantages in trawling with two 
boats at night and in bad weather. It is often difficult to 
maintain a constant distance between the vessels and, in 



Pareja trawler has wing bollards on the bulwark behind 
the snatch blocks and the towing block amidship at the 
deck house. Although the net is shot over the stern, it is 
hauled over the bow, where there is another pair of 
rollers; on either side of the latter, modern vessels have 
in addition two protective rollers. Vessels with whale 
backs have yet other protective rollers at the rear end, as 
shown in fig. 101. 

The full codend is brailed until it can be hoisted by the 
fore derrick. The Pareja trawler cannot be used as a 
single trawler. 

Tegori trawler 

The Teguri trawlers are small boats operating in the 
East China Sea and the Yellow Sea. The engine room 
and deck house are aft, while the fish holds axe arranged 
in the foreship. The shooting operation is carried out by 
the two boats but the net is hauled aboard over the stern 
of one boat The warps are hauled by two drums on 
either side of the deckhouse and thereafter wound on 
reels behind the forecastle. The trawl winch is driven by 
the main or auxiliary engines through a countershaft 
Most of the vessels shown in fig, 102 are 50 to 130 GT, 
of steel or wooden construction. Smaller boats of tradi* 



FISHING ftOATS OF f HE WORLD : 2 TACTfcGS 



tkmal type as shown in fig, 103 are also used. The average 
trip lasts three weeks and the crew numbers 12 or 13 men. 




There Is also a need for instruments to control con- 
tinuously the depth of the net. Special equipment is 
wanted to transmit the data from the depth measuring 
device to the bridge. This might be wireless or by a cable 
from the net. If it is done by cable, then an additional 
cable drum or winch would have to be installed. 




102. Japanese Teguri steel or wooden two-boat trawler of 
SO to 130 GT 



tranter 

The Tuckzeesen trawlers operate with equipment used 
in one-boat trawling. An inshore trawler or "trawl 
smack", well known in North European waters, is used, 
with dock equipment similar to that of the large side 
trawler. There are two small gallows but sometimes only 
one forward gallow with two rollers for two warps. The 
wheelhouse is placed aft and the net is only handled on 
the working deck forward of the wheelhouse. Trawl 
winch, guiding rollers, foremast and hatches are arranged 
as on large trawlers. Shooting and hauling is done by one 
boat, towing by both. The crew of the shooting boat 
has in some cases to be bigger due to this reason. 

MIDWATER TRAWLER 

While the trawl is considered the most important gear 
for catching fish on or close to the bottom, it can also be 



Fig 104. Danish two-boat pelagic trawl (Larsen type) 

Two-boat type 

As in two-boat bottom trawling, there is no frightening 
effect on the fish, and the trawling speed is sometimes 
greater. These advantages have contributed to the success 
of the Danish net shown in fig. 104, which was invented 
by Robert Larsen. 

Two-boat fishing limits the size of the vessels, and 
operations are difficult in bad weather, from wind force 
Beaufort 4; and for larger vessels, 6. 

One-boat type 

Fishing with one vessel is less dependent on the weather. 
The disadvantages are that the lines of the net cross the 




Fig. 103. &naUTeguritrawlerhavingacrewofl2or 13 men 



Fig. 105. On+boat pelagic twl of British Columbia 



operated away from the bottom. But, until the invention 
of fish-detection instruments, it was not possible to 
ascertain the depth at which the fish were swimming, 
there are still problems to be solved before success in 
pelagfc trawl fishing can be assured. In particular, them 
is a ne(xl to acquire biological knowledge of the behaviour 
of the fish, especiaHy herring and similar species. 



fish shoal, and the otter boards may also cause dis- 
turbance. Moreover, if the vettel sails over the shoal the 
fish, if high in tile water, may be frightened. These 
difficulties may explain why this kind of fishing has not 
been very sucoessftil until recently. 

At least two types of pelagic one-boat trawb have 
become well known : the Canadian net, operated over the 



IU2J 



FISHING METHODS AND DECK ARRANGEMENT TRAWLING 

stern, as shown in fig. 105 and 106, and the Swedish net, 
designed by K, H. Larsson, operated over the side: the 
latter system is shown in fig. 107. The deck equipment is 
the same as used for bottom trawl nets. The codcnd 
of the Canadian trawl is opened at the side and brailed. 
This enables finer net material to be used but some addi- 
tional deck equipment is necessary for brailing as shown 
in fig. 106. 

Recently, indications from an echo sounder transducer 
placed on the headrope of pelagic trawls could be 
transmitted by cable to the echo sounder recorder in 
the wheelhouse. Because the depth of the trawl can be 
adjusted by altering the ship's speed, the depth can be 
adjusted to that of fish shoals, indicated by the ship's 
echo sounder. As a result of this technique very large 





Fig . 106. Brailing of a Canadian pelagic trawl net (Barraclough and 
Johnson, 1955) 



Fig. 107. Swedish one-boat pelagic trawl (Larston type) 

catches were made by both small and large German 
trawlers. 

FUTURE PROSPECTS 

Future deck arrangement and the method of handling 
the gear will depend to a large extent on trends in catch- 
ing, handling, processing and transport of fish. There is 
a trend towards the larger trawler with more store room 
and greater engine power, but the limitations in fishing 
techniques and other factors tend to restrict this develop- 
ment. 

The need to cut down travel time between port and 
fishing ground calls for vessels of improved design and/or 
with greater power. They must also be able to fish in 
rougher weather and thereby increase the fishing time. 

The operational method of stern trawling permits 
building a vessel of approximately 300 ft. (90 m.) in 
length, which is larger than the present side trawlers, and 
suggests a development of the stern trawler towards a 
large combined fishing, transport and processing vessel. 

The advantages of the existing stern trawlers with a 
ramp suggest the development of a smaller craft of this 
type, also with a ramp. Design studies and experience 
suggest that a vessel of 100 to 120 ft. (30 to 35 m.) in 
length may have a future. It might become a new type of 
"distant water trawler" without transport functions, sea- 
worthy and efficient. A stern trawler of less than 100 ft. 
(30 m.) in length, with a wide net roller instead of a 
ramp, also seems to have a useful future. 



{H3 I 



CENTRALIZED CONTROL OF TRAWLERS 

by 
A. C. HARDY and H. E. H. PAIN 

The appearance and interior pf trawlers have altered much over the yeara, mainly due to the advent of mechanical propulsion, the 
application of modal test mute, and the development of navigation and fishing instruments and equipment. To accommodate the added 
ttpoaratm and to give centralized oontml* the brito has It is becoming the nerve centre of the vessel The paper describes 

this progress and explains the basic requirements for centralized control. A few examples of bridge layouts are given. 



LBS COMMANDES CENTRALISEES A BORD DES CHALUTIERS 



L'a 



t et rintirieur des chalutiers ont beaucoup chang6 au oours des 



surtout a la suite de 1'avtoement de la propulsion 



<k disposition de la passeiUe. 




CENTRALIZACION DE LOS MANDOS EN LOS ARRASTREROS 

Con el transcorso de los afios han ctmbiado muofao el aspecto y la distribucidn interior de los arrastreros, debido principalments 
*I advenimtento de la propuls&n mectafca, la apiicaci6n de los resultados de ensayos de modelot y el perfeodonamiento de los instrumentoe 
y material de aavegactdn y pcsca. Pfcim qoe altorgase todos estos apanrtos y centralizar lot mandos del barco, se ha tenido que aumentar el 
tamafio del puente, quc se ha convertklo en el centre neurilgico de la embticacidn. En la pooeocta se describen estos adelantos y se las 
i fondamentaJes para centralizar los mandos. Los autores dan algunos ejemplos de distribution de puentes. 



f I ^HE trawler of today is an expensive and intricate 
I piece of fishing mechanism. It is expensive largely 

JL because it is intricate, and it is intricate because of 
the devices and equipment it carries; yet no trawler 
carries anything other than of a severely utilitarian 
nature. Rapid advances in technology have affected the 
shape, altered the profile and improved the interior of the 
trawler. 

In the profile, not the least important portion is the 
bridge. In fact, the bridge of today is the nerve centre 
from which every function of a trawler's operation 
other than cooking 4s controlled. In the 80's, the bridge 
was merely an open space above the engine room with a 
steering wheel, a compass, and a voice pipe to the engihe 
room. The masts were still fitted in the same position 
they had occupied when the trawler was propelled by 
sails. Indeed, sails were often used in trawlers on the 
mainmast up to the outbreak of World War II. 

Today from the bridge or nerve centre the speed and 
direction of the ship is controlled, the fish are detected, 
the trawl modi is operated and ship-shore communica- 
tion is maintained. Instruments give the skipper exact 
information about his vessel's trim and stability, and the 
speed of the various machines, and he has a "broadcast" 
weather map showing the approach of bad weather, so 
that he can avoid it. Electronics now play an important 



part in the trawler's nerve centre, and automation is 
increasingly being adopted. 

Instrumentation and automation have increased the 
size of the bridge and altered its appearance. The more 
or less open launch of the 1880's is developing into the 
totally enclosed ship of the 1980's. 

Idea of centralized control 

As more aids to control the trawler from the bridge come 
into use, they are installed at positions most convenient for 
the user and to meet many individual requirements, but in 
general the arrangement follows the same broad pattern. 

Fig. 108 shows the general layout in {dan and front 
elevation of a modern deep-water trawler's bridge, and it 
also illustrates the basic requirements in terms of func- 
tional instrumentation. 

In aircraft, control is concentrated in the pilot's cock- 
pit. Here the essential control requirements in terms of 
functional instrumentation have increased to the^point 
where it is hardly possible to find space for a single extra 
instrument or information dial Fig* 109 shows the cock* 
fit in a modern commercial aircraft. All the information 
sources cannot be studied at once, nor do they need to 
be, but their grouping, logically placed with preference 
given to the moot vital, is an excellent example of 
centralized control and information services. 



[114] 



COMMAND OF OPERATIONS CONTROL OF TRAWLERS 



Similarly, in ships, die grouping ii basically universal: 
Centrally placed steering position, engine control tele- 
graphs at each side of the bridge, duplicate steering 
. control in certain classes of trawler, with winch and other 
controls conveniently positioned, together with radar and 
echo-sounding or ftsb-finding displays. 

Fig. 106 shows the common information services and 
functional controls. The arrangement is wasteful of 
space and all units cannot be said to be conveniently 
placed to meet all situations. The illustration is a good 
example of conventional equipment It will be noted 
that a gyro compass steering repeater is fitted. 



vided anywhere in the vessel by means of electric 
repeaters. 

More than 30 years of use has proved the considerable 
fuel saving with automatic steering. In addition, steering 
engine wear is reduced and the human helmsman is 
released. 

Most automatic steering systems using a gyroscopic 
compass as datum also have electric hand steering. Its 
reliability has also been proved. Very much less manual 
effort is required to steer, the course is more accurate, 
and fuel and time are saved. 

It is of interest that a helmsman using the hitherto 





. 108. Conventional wheelhouse of a modern middle-water or deep-sea trawler illustrating 
the basic information and control services 



BASIC COMPONENTS FOR CENTRALIZED 
CONTROL 

Hydraulic and electro-hydraulic steering engines are still 
the most suitable for large fishing vessels. In the interests 
of safety at least one magnetic compass must be carried 
in all types of vessel 



The electric gyroscopic north-seeking compass has been 
generally adopted in ocean-going vessels. Its advantages 
are the absence of errors due to variation and deviation, 
accuracy in polar latitudes and also reliability. Modern 
gyroscopic oompaspes am small and robust and present 
no siting problem. Compass information can be pro- 



conventional telemotor steering control, but having a 
gyroscopic compass as course indicator, can maintain a 
more accurate course than he can with a magnetic 
compass. This particularly applies in heavy seas and high 
winds. Again there is a saving in fuel. A telemotor 
transmitter control cap be replaced by electric steering 
control with complete safety and increased efficiency. 
As a safety precaution, the necessary wiring to the steering 
engine should be duplicated, as should also, and 
separately, the connection to the steering engine. With 
electric control, duplicate steering positions are simple 
additions; they can, of course, be remote from die 
bridge. 
Hitherto, the conventional wheel has been almost 



[115] 



FISHING BOATS OF THE WORLD : 2 TACTICS 




Fig. 109. Cockpit of a modern airliner illustrating centralization and concentration of Information and control services 



universally used to actuate the rudder. With electric 
control, a complete wheel is unnecessary and can even 
be omitted entirely. 

Magnetic wto steering 

A magnetic compass as datum can also be used for 
automatic steering. It cannot give as accurate a course, 
but is efficient and by comparison inexpensive. It is, in 
general, more suitable for the smaller vessels. , Here also, 
remote control can be provided. 

Magnetic compasses, with remote repeaters, are 
available and may have advantages in tains of cost, 
where the extreme accuracy and other services provided 
by a gyroscopic compass are not required. 



The remote repeaters of transmitting compasses can give 
inputs to the radio direction finding indicator. With gyro 
input it is of evident advantage to read off true bearings. 



Radar 

In the latest development of radar, sometimes called 
"true motion*', the gyro input has made it possible for 
the radar console to provide azimuth stabilized true 
motion display: off-centred relative motion display; true 
motion display using log speed input, and true motion 
display using manual speed input. 

In effect, the officer-in-charge can be given a picture 
showing the positions, movements and tracks of all ships 
within range in true perspective to his own ship. 



Many types of electric rudder angle indicators are 
available. With direct-acting electric steering control 
can readily be incorporated the rudder angle indicator. 

Log 

The most modern logs transmit information electrically 
and, as has been said, can supply one of the automatic 



[116] 



inputs to "true motion' 
also be displayed. 



COMMAND OF OPERATIONS CONTROL OF TRAWLERS 
radar. Distance travelled can 



Echo 

Many types are now available to meet two basic require* 
ments navigation and fish location. For accurate and 
speedy detection, and identification of fish, a combination 
of recorder and visual display, similar to the conventional 
radar presentation, represents a considerable advance. 
The recorder will give an indication of the presence of 
fish and a certain measure of quantitative information. 
For detailed examination the cathode-ray tube enables 
extremely accurate and rapid assessment to be made. 
An aural system can give notice that fish echoes have been 
detected. 



r.p.m., and propeller-pitch, with provision to stop the 
engines, and also discontinue the automatic speed control 
to ^obtain full-engine revolutions when necessary. A 
second lever alters the relationship between pitch and 
power. 

Further advances enable complete control to be 
exercised from a singk lever. This regulates fuel supply 
and shaft speed, and at the same time controls pitch to 
meet any change in ship condition. 

Such systems can also provide a second or "slave" 
control position in addition to that from the engine room. 

Propeller-pitch and engine mutation indkators 

These are ancillary to main engine controls and are 
positioned at the control position. 



CHANQI-OVt* LEVER 
AUTOMATIC NAVIGATOR 




Fig. 110. Wheelhouse of a middle-water or deep-sea trawler illustrating a concept of 
centralized information and control services to provide maximum economy of space ana 

manpower 



As an ancillary to the fish detecting devices, which it 
must be remembered only indicate when fish have been 
found and not how to find them, it is required to know 
accurately the depth at which the trawl is towing. The 
trawl can then be adjusted to the known depth of fish. 



Engie and propeller control 

Where the main propulsion machinery is internal com- 
bustion or electrical and also where controllable-pitch 
propellers are used, complete remote control can be 
exercised from the wheelhouse as well as from the 
engine room. A single lever can select both engine 



Engine room tekgraph 

The conventional engine room telegraph has been 
developed into indicating telegraphs and control levers 
which can be desk-mounted in juxtaposition with other 
controls. 



Ctowd circuit tekvfatoo 

For stern trawling, closed circuit television, to observe 
operations that would otherwise not be visible, may be 
considered. Provision can be made for its incorporation 
in any scheme of centralized control 



[117] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



TYPICAL LAYOUTS HP CENTRALIZE 
CONTROL 

Three main claret of fishing vessels are chosen as repre- 
sentatives of the vessels where centralized control would 
show the greatest saving in construction cost, top hamper, 
and operating expenditure? 



The "middle-distance" and "deep-water" trawler 

The fish factory trawler with or without stern trawl 
facilities 

The fish factory parent ship or other large vessel. 



engine controls are at hand, as are also the winch button 
and tog. 

For normal control while on passage the information 
sources art placed around the main steering position. 
The master transmitting gyro compass is used as the 
steering repeater. An indicating echo-sounder unit is also 
placed where most easily seen when navigating in confined 
waters. The radar unit is placed to give maximum 
accessibility without in any way interfering with either 
of the two steering positions. 



TftfC CONTROL I* 




Fif. 111. Centralized command control in (lie wkeelhouse (above) and remote control at the 
stern trawl position (below) in a fish factory trawler 



Fig. 110 shows a centralized lay out suitable for amiddfe- 
distanoc or deep-water trawler with starboard control of 
fishing. Although the vessel can remain in automatic 
steering, the "push-button" controls at the starboard 
wing can over-ride automatic steering and direct the 
vessel as necessary. 

The "fish indicating" recorder, while not obstructing 
direct vision, can be kept under constant observation 
while the ancillary cathode-ray display unit is also 
immediately accessible. Engine room telegraphs or 



Fish factory trawitf 

Fig, 111 illustrates a control layout applicable to the 
fish factory trawler with stern trawl and the stern control 
position. The starboard wing control position is not 
required. Provision is made for closed circuit television 
display to provide immediate visual information about 
operations astern. 

A control console for the after position is shown. This 
includes push-button steering together with rudder angle 
indicator, main engine controls and a cathode-ray display 
for examination of fish echoes. 



[118] 



COMMAND OF OPERATIONS CONTROL OF TRAWLERS 



At both the wheelhouse and stern control positions, 
engine room telegraphs could be substituted for the main 
engine controls, if required. 

Large TCMd 

Fig. 1 1 2 and 113 shows the centralized command concept 
for the largest type of vessel, including the fish factory 
and mother ship. 

Two schemes are shown. Both include a deck-head 
mounted, double-faced rudder angle indicator, visible 
from anywhere in the wheelhouse or wings of the bridge. 
Both also show the reflector type magnetic steering 
compass. 



engine room is considered more practicable in larger 
types of vessel. 

This provides an opportunity to emphasize the safety 
factors incorporated where auto-electric control is used* 
If wiring and, separately, the connection to the main 
steering engine is duplicated, it is then possible to have 
hand electric control and automatic steering available 
through one set of connections with push-button control 
via the other set at standby. 

Using auto-electric control, change-over to any of the 
three methods of steering can be accomplished in 
seconds. Further, the complete cycle of change-over is 
duplicated. 



flUTQM4fftC MJIV KUtfQII 
CQLJftftC 





OOOaoOOOOQ 



Fig. 112. Centralized control in a fish factory or large mother ship 



Fig. 112 shows the main steering position embodied in 
central control. The command position is placed imme- 
diately to starboard with the engine revolution indicator, 
log and echo-sounder indicator conveniently displayed. 

Fig. 113 shows the main steering to the rear of the 
central control Although shown amidships, there is no 
technical reason why this main steering position should 
not be elsewhere in the wheelhouse if desired. Push- 
button steering is included in the main console. While in 
automatic steering, the officer-in-charge can take imme- 
diate over-riding steering control whenever required. 

Control positions remote from the wheelhouse could 
be provided if necessary. Control of main engines is 
replaced by engine room telegraphs because at the present 
stage, control of main propulsion machinery from the 



All these proposals of centralized control have the 
common feature of leaving much of the port side dear of 
obstructions. Larger ocean-going vessels have a trend 
towards combining the chartroom and wheclhouae. By 
careful attention to lighting and screening, the port side 
of the wheelhouse could be used as a chart table ami for 
the automatic navigator, electric course recorder, 
weather map display or other instruments concerned in 
navigation. Where the size of the wheelhouse does 
not permit this, the space can still be used for a chart 
table. 

Other instruments, particularly internal and radio 
telephones, could very easily be incorporated in tlie 
control consoles. Such units, as loudspeakers and switch 
boards could be sited conveniently on the after bulkhead 



[119] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



The instruments illustrated are not comprehensive and 
tie only representative of the many available. 
The design of centralized control must be flexible and 



steering, the remote steering facility can be particularly 
valuable in saving manpower, always provided due regard 
is paid to lookout. 



CONTPQL UNIT 




CHANGEOVER 




ECHO SOUNDER INDICATOR 

REFLECTOR TYPE COMPASS 
(ON DECKHEAD OVER) 



STEERING REPEATER 

AUTO ELECTRIC STEEPING COLUMN 
Fig. 113. Alternative arrangement to fig. 112 with separate steering position 



adaptable to meet individual requirements. Easy access 
to die various instruments is required for servicing and 
can be achieved by removable panels or components. 



A degree of centralized control can also be achieved, with 
resultant saving, in smaller classes of fishing vessel than 
those mentioned. For instance, the systems using a 
magnetic compass as datum and providing automatic, 
hand electric and remote control of steering as an addi- 
tion to the normal system, are considered particularly 
useful in drifters, seiners and line fishing boats. 
As well as the physical relief afforded by automatic 



Conclusions 

All of the designs shown are entirely practical and are 
intended to show how to achieve greater efficiency and 
economy in control. 

An early decision by the owner to take advantage 
of centralized control would enable the naval archi- 
tect to prepare the most economical wheelhouse 
design leading to a change in the size and shape of 
the bridge and a saving in weight and cost. Installa- 
tion problems would be modified and streamlined. An 
economy in manpower would be achieved with, at the 
same time, reduction in fatigue and increase in operating 
efficiency. 



[120] 



DESIGN OF TRAWLERS DISCUSSION 



Review of related papers 

DR. J. SCHARFE (FAO, Rapporteur): Apart from von Brandt 
and Btrkhoff's background paper, information on specific 
trawler deck design is given, for instance, by Ringhaver 
who describes the Gulf shrimp trawler in Florida. The 
forward position of the, deckhouse of these boats is said 
to go back to the old times of hand hauling the gear. The 
ample working space aft although very welcome is not essen- 
tial for the power handling of the gear. Instructive drawings 
are given, illustrating the recent radical change from the 
conventional one-net to the modern two-net method which 
demanded a considerable change of the rig. The new method 
for which two 40 ft. (12 m.) otter trawls are towed simul- 
taneously from strong outriggers, as many other subjects to 
be mentioned later have also been described from the gear 
point of view in Modern Fishing Gear of the World 
(Kristjonsson, 1959). The operation can be taken as rather 
well mechanized. A similar two-trawl method of shrimp 
trawling is common in the Netherlands and Germany with the 
difference that beam trawls, instead of otter trawls, are used. 
A sketch of the rigging of such a boat is given by Boogaard 
(fig. 695 and 696). It may be mentioned that considerable 
risk can be attached to such outrigger trawling in case one of 
the trawls gets caught at the bottom. When towing with a 
strong tide, only a very quick action, namely releasing the 
respective warp, can prevent the boat capsizing. An auto- 
matic device for effecting this release in proper correlation 
with the pull of the remaining warp would be a great help. 

Boogaard also touches the question of winch drive by giving 
details of construction, performance and wire capacity of the 
trawl winches of four conventional types of Dutch craft. 
The smaller boats have belt drive from the main engine. The 
bigger trawler-drifters use an auxiliary diescl of 100 h.p. and 
the still bigger trawlers of 132 ft. (40.25 m.) LOA have 
hydraulic drive. 

The pro and contra of electric and hydraulic winch drive 
for big deep sea trawlers is discussed by Stokke (p. 26). The 
somewhat smaller efficiency of the hydraulic drive is said to be 
compensated by its smaller size, which not only can save 
engine room space but also allows for direct attachment of 
the oil motor to the winch. The considerable space otherwise 
needed for the winch motor can be used, for instance, for 
crews 9 accommodation. This is an advantage particularly for 
smaller craft. 

Hauling trials described by Dickson provide information 
on the relation of hauling speed and power output of the 
winch at different warp loads for two typical U.K. trawlers. 
Dickson furthermore stresses the need for considering the 
stability when converting for instance Danish seiners into 
trawlers. The well known stiffness of the Swedish motor 
cutters enables them even to tow with both warps at the 
top of the aft gallows. They, therefore, need no sliphook 
and avoid the working of the warps in the sliphook which 
Dickson mentioned as mult of too short a distance between 
aft gaUowand towing Mode. More tender boats might come 



in a dangerous position when heaving with conventional 
equipment broadside in bad weather and a strong tide with the 
gear caught at the bottom. 

Seakindliness has a bearing on the present subject in so far 
as it affects the working conditions on deck. Mockel collected 
data of the metacentric height (GM) of five commercial 
trawlers. He found that a GM between 2.3 and 2.6 ft. (0.7 
and 0.8 m.) is a reasonable compromise for those vessels and 
is most agreeable for the crew. Lower values give the feeling 
of insecurity. High values result in too much stiffness. In 
both cases, particularly in the latter one, the vessel ships 
much water in bad weather interfering with the ability and 
safety of the crew working on deck. Such vessels consequently 
have to stop fishing earlier. Zwolsman states the average 
metacentric height for modern standard Dutch fishing boats 
of about 72 ft. (22 m.) LOA to be 2.56 ft (0.78 m.) fully 
equipped but without ice. The crew are said to consider these 
boats as very seakindly. 

Besides the operation of the gear, often a greater part of the 
crew's work on deck is devoted to the care of the catch. 
Reay and Shewan (p. 200) point out that the fish quality and 
the time it can be kept in good condition on ice, depends 
very much on the time which elapses before it can be cooled 
down. The process of gutting, cleaning and stowing should, 
therefore, be accelerated as much as possible. Mechanical 
washing machines and chutes to direct the fish into the 
fishroom have already considerably contributed to diminish 
delays. But there is still a wide field for improved mechaniza- 
tion of fish handling on the conventional trawlers with respec- 
tive changes and additions in the deck designs. 

De Wit states that herring drift-netting in the North Sea is 
declining. Consequently in Holland drifters often are replaced 
by small trawlers. Existing drifters with sufficient engine 
power are fitted with gallows and trawl winch to serve as 
combined drifter-trawlers and also new combination vessels 
have been designed. In Germany the same tendency can be 
observed. Until now these combined vessels trawl over the 
side which still is the most common method in northern 
European countries. De Wit now proposes a revolutionary 
design combining stern trawling with a stem chute with 
drift-netting from a sheltered 'tween deck. 

This leads to the most recent development, namely stern 
trawling, particularly with a stern chute. The conversion from 
side trawling to stem trawling with a stern chute has strongly 
affected the traditional deck design and brought forward a 
good deal of new ideas and improvements in favour of the 
so badly wanted mechanization of trawl operation. Heinsohn 
gives a comprehensive description of the time German 
stern trawlers in operation to date, comparing and dfcnmfting 
also their different deck design and equipment. Ordinary 
trawl winches should serve the purpose but for convenience 
an additional pair of drums or capstans have been installed 
in two vessels. Electric drive, installed in two boats* 
seems to have advantages over hydraulic drive became of its 
better flexibility and the easier possibility of using the winch 



[121] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



generator as additional propulsion power. A long distance 
between the winch and the upper edge of the stem chute 
is advantageous for hauling in the about 183 ft. (56 m.) long 
net with die catch. The distance should not be less than 
about 70 ft (21 m.). On Heinrich Mtins it is even 97 ft. (30 m.). 
So with two additional pulls the catch can be brought on 
deck. For the last pull for heaving the loaded codend, 
now a tackle is used in line with the slope of the stern 
chute. This eases the pressure and wear on the codend and 
lengthening piece. With nylon codends having special 
strengthening, more than 25 tons are said to have safely been 
brought on deck in a single operation. This means a con- 
siderable saving in time compared with the splitting of the 
catch of side trawlers. The average time taken on a com- 
mercial trip of Sagitla was 24 min. for Hie otter boards to be 
out of die water. Of this time 14 min. were spent in average 
for net repair and removing giiled fish and only 10 min. for 
dipping and unciipping the otter boards, hauling the trawl on 
deck, emptying the codend and shooting again. The crew is 
released from all heavy work such as hauling in the net and 
it works well protected and in safety. The fish is gutted or 
further processed under deck, washed by a machine and 
carried to the hold by means of conveyor belts. This most 
promising development should most carefully be considered 
for application to different fishing conditions. It seems well 
suited to solve quite a few trawling problems. A standard 
deck design, as, for instance, is found in side trawling, has 
not been established yet so that exchange of practical experi- 
ences with the different systems would be most fruitful. 
Ease and speed of operation is one of the main points of this 
method. There are, however, some doubts regarding the 
quality of the fish hauled in a big bulk, which should be 
discussed. 

One aspect of the ideas on centralized control of trawlers 
put forward by Hardy (p. 114) might shortly be mentioned 
already now. It regards full winch control from the bridge 
which at the moment is still wishful thinking. A partly 
control, namely the release of the warps from the bridge in 
case of the gear being caught at the bottom, has been installed 
for instance in some new German vessels. But there are 
strong points in regard to efficiency, labour saving and safety 
which make a full central winch control during the whole 
gear operation desirable. This is a problem worthwhile to be 
taken up by marine engineers. The present trawl winches 
might not be suitable for such central control. So new designs, 
eventually with separate drive systems for the warp drums 
and capstans and suitable brakes, could easily lead to a 
complete change of winch arrangement and warp conduct and 
consequently to a thorough redesign of the deck equip- 
ment of certain trawler types in favour of improved 
mechanization. 

PROFESSOR A. VON BRANDT (Germany): The importance of 
trawling is underlined in Hardy's first paper. For the North- 
western part of Europe, for instance, the trawl is the most 
important gear for harvesting the sea. Trawling as we know it 
now, however, is a comparatively new method and there are 
stifl old skippers who have participated hi it from its beginning. 

It is not surprising that, for instance in Europe and East 
Asia, very old types of trawling gear are being used tide by 
tide with the most progressive gear from one and the same 
port; there are beam trawls and otter trawls, and there are 
bottom trawls and floating trawls. 

Trawling is mads from a very wide range of sizes and types 
of craft; there are small sailing boats and high-powered 



trawlers, there are inshore and deep sea vessels, and the towing 
speed might vary between 0,5 and 5 knots. 

There, naturally, is a close correlation between the type of 
the gear and the type and equipment of the boat; the gear 
influences the boat and the boat might eventually influence the 
gear. The introduction of power propulsion was indispensable 
for the development of modern trawling. The exploitation of 
the deep sea required bigger and bigger craft, these, on the 
other hand, allowed for bigger gear. 

This shows that, first, boat and power must be a sound 
unit: this is underlined by the several contributions dealing 
with propulsion problems. The solution is important not only 
for the big trawlers but perhaps even more for the small 
ones which usually are treated as less interesting for rational 
approach, and, therefore, are almost forgotten. 

There must secondly be a close correlation between the boat 
and power unit on one hand and the fishing gear on the other 
hand. Coming from a Gear Research Institute, Professor 
von Brandt felt quite clearly the wide gap between the present 
state and the effective solution aimed at. A great deal of 
improvement is needed before the powered boat together with 
the gear will become a very efficient unit, and this demands 
efforts from the naval architects, the fishermen and the gear 
technologists working in close collaboration. 

Until now, only technical matters have been mentioned, 
i.e. the boat, the power and the gear, which should be a 
proper unit. But besides this there is a further very important 
point which has to be taken into consideration: the crew. 
There are model tests with boats and with gear, but until now 
the fishermen seem to have been neglected. In this respect 
he was not thinking of better accommodations for living and 
sleeping on board or safety at sea. A lot has recently been 
done in this field in different countries. He was thinking of 
working physiology. 

If a farmer's wife wants a new kitchen, she can rely on 
extensive studies concerned with the right placing of table, 
water tap, and even to avoid unnecessary steps. If a farmer 
needs a new spade, lots of tests have been made about the best 
shape and length of the handle to obtain highest efficiency. 
But looking at a trawler's crew working, it is quite obvious 
that nobody has ever seriously cared how their operation 
could be improved. There is a wide field for extensive time 
and motion studies, on proper deck design and equipment 
and its optimal placing. Until now it obviously made not much 
difference to the designer if a basket had to be lifted 3 ft. (1 m.) 
high or only 1} ft. (im.) or if it had to be used at all. The 
fishery is in this respect in the same position as all industry 
with the difference that on land this demand has long been 
realized. In the fisheries of highly developed countries with a 
high standard of living and the consequently growing diffi- 
culties to find trawler crews for the difficult job of handling 
the gear to a great extent with their own hands, the 
demand for rational mechanisation becomes more and more 
pressing. 

Fortunately there is now a promising indication that the 
trawl fishery gradually becomes conscious of this need. The 
development of the big Northern European stern trawlers, 
for instance, is one first and very important step in this direc- 
tion. It is to be hoped that the great interest caused by this 
development will stimulate similar efforts in other trawl 
fisheries too. 

MR. J. pRQSKift (Canada): Since the trawl has been specifically 
developed for groundfishing (all species except halibut) the 
impact of this type of gear on total catches of groundfish 



(122 J 



TRAWLING DISCUSSION 



shows son* interesting result* for the Canadian Atlantic 
coast. 

An estimate of contribution to total landings of groundftsh 
in 1957 by trawler* was as follows: 

Percentage contribution to total groundfish landings 
By trawler* under 70 ft. (21.4 m.) LOA 12 per cent. 
By t ra wlen over 90 ft. (27.4 m.) LOA 30 per cent. 

The small trawlers were developed under the fleet moderni- 
zation programme for the Atlantic coast and are fishermen 
owned. The large trawlers for the most part are company 
owned. 

Brandt and Birkhoff in their paper also suggest the develop- 
ment of stern trawlers of less than 100 ft. (30.5 m.)* Three 
such craft were developed on the Atlantic coast by the Depart- 
ment of Fisheries of Prince Edward Island. These trawlers 
were 50 ft. (15.2 m.) LOA powered by a 76 h.p. diesel engine. 
Although these craft proved to be suitable for scallop drag- 
ging, they were found to be unsuitable for groundfish fishing 
for the time being. 



Stem handling 

MR. H. R. BARDARSON (Iceland): Stern trawling is a remark- 
able new development from the usual side trawling. However, 
this new type of handling the gear seems to have more advan- 
tages when adopted on big factory ships than on the small 
sea-going trawlers of 600 to 850 GT. Icelandic trawlers come 
almost entirely within these tonnage limits and none of them 
trawl over the stern. In Iceland, they have up to now no 
experience with stern trawlers, but they have been considering 
very carefully whether this type of ship would be a step forward 
for their trawling industry. 

Iceland is not basing the fishing industry on factory ships, 
as there are freezing plants on land all around the coast, and 
the task of the fishing vessels is to bring first rate fresh fish to 
the harbours. The freezing plants are much closer to the 
fishing grounds than in many other countries. The big type 
of factory trawler with freezing plant on board is very expen- 
sive, not the least owing to the large crew it must cany. 
Although mechanization can be used on board for preparing 
the catch and freezing, the crew have to be paid all the time 
they are on board, whereas on land workers are only paid 
for actual working hours. Owing to the difficult crew situation 
in Iceland at present, with a need for more fishermen, the 
factory ship would be a big problem to solve. 

The question is then whether the stern trawler would still 
have many advantages over other types of trawlers in the size 
group of 600 to 850 GT for iced or cooled fish only. He felt 
that the crew would have better working space and the bigger 
freeboard might also result in less icing. These are important 
advantages. 

The motions on the aft end of a vessel are not so comfortable 
as in the midship region. He considered that it would be 
possible to fish in worse weather with the conventional ships 
rather than with the new ones, considering the size of ship. 
Iceland is following with interest the results of the first stern 
trawlers. It had been said that stern trawling still results in 
difficulties in handling a completely filled codend, as the whole 
net is hauled at once. He had also heard that this has caused 
damage to fish in the lower part of the net through pressure 
when the net is hauled up the ramp. 

Although stern trawlers are very interesting, he felt that 
some alterations would be necessary for Icelandic conditions, 
and he considered this type of trawler to be still in the 
experimental stage. 



MR. A. HUNTER (U.K.): The characteristics of modern side 
fishing trawlers permit high economical speed and provide a 
safe platform for fishing in bad weather up to force 7/8 on 
the Beaufort scale. More knowlege of the reaction of a trawler 
form to varying sea energy spectra and the best routing based 
on more use of weather prediction may enable quicker 
voyages to be made. This is important from the aspect of 
fuel costs where the fisheries are remote. Stern trawling must 
nevertheless always attract the attention of owners and 
builders. Were such vessels comparable in resistance? Model 
experiments carried out with a good trawler speed form 
modified for a stern ramp showed that with the lower portion 
of the ramp immersed the resistance increased by 20 per cent. 
On this basis 20 per cent, more fuel would be consumed. 
If fish processing were done on board speed was of less con- 
sequence, but generally larger ships were involved. In Britain 
it had been stated that factory ships of the Fairtry type 
caught in one year about the equivalent of two orthodox 
trawlers, while the cost was said to be as much as that of three 
or four orthodox trawlers. In these ships commercial con- 
siderations could not ignore the sociological effect on larger 
crews required to spend considerably more time at sea, 
often in bad weather conditions. There may therefore be a 
place in the fishing economy for the normal size of trawler 
bulk freezing part of the catch at sea. This did not mean that 
builders were opposed to stern trawling and they would always 
undertake the construction of vessels which owners considered 
best for their purpose. 

MR. J. C. E. CARDOSO (Portugal): Although no big stern 
trawlers are at present operating in Portugal, he believed that 
stern trawling has great possibilities and shows advantages 
over the traditional method. It is, however, difficult to con- 
vince fishermen to take up a new fishing method. At present 
the Government is building a research ship of 190 ft. (58 m.} 
length which will be equipped for stern trawling. This vessel 
should serve the purpose of convincing owners and fishermen 
of the advantages to be derived from the adoption of stern 
trawling. 

MR. J. G. DE Wrr (Netherlands): Stern trawling results in an 
arrangement in which the crew's quarters are in the forward 
part of the vessel. This is of no advantage to the crew. All 
new vessels in the Netherlands have crew quarters aft. He 
would ask as to what the advocates of stern trawling have to 
say about this question. 

SIR FRED PARKES (U.K.) felt that German trawler owners did 
not favour stern trawling for their normal size vessels, a 
method which seemed to be of advantage mainly for large 



Distant water trawlers were very costly, about 300,000 
($840,000) apiece. One should strive to evolve a vessel that 
brought fish to port in larger quantity and in good quality at 
lower costs. His company had ordered six small vessels of 
100 ft (30.5 m.) length, with controllable-pitch propellers. 
This was a new venture for home water fishing. 

MR. H. HEINSOHN (Germany) said that his company was 
designing stern trawlers of the size of ordinary side trawlers, 
and three had already been operating successfully for two to 
three years. Although there was at the moment still a wide 
field for improvement, because stern trawling with deep set 
trawters was a new venture, the evidence offered by practical 



[123] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



oporattoa should act be tenoned and should have move 
weigh! than theoretical conclusions. 

For exampto, the quality of the catch was doubled because 
of the big pressure in the codend. However, landing statistics 
and reports from fish merchants showed definitely that this 
was /to/ the case. On the contrary, there were indications that 
the average quality was better, especially on long trips. One 
of the moms might be that the fully packed codend is lifted 
on board Quickly* and there is a shorter death struggle than 
with side trawling when the bag has to be split when a large 
catch is made. The fact that the fish before gutting are 
stowed below deck and protected from the light may also mean 
improved quality, as well as the mechanical handling, washing 
and quick transport to the holds after gutting. 

It has been said that stern trawling, especially in smaller 
vessels, was impossible in bad weather and that a stern 
ramp would only be suitable on big factory vessels. Here 
actual experience, too, proved this statement to be wrong. 
The stern ramp should follow the movement of the waves as 
closely as possible, which seems more likely to happen with 
smaller vessels provided the most suitable course during 
hauling and shooting operations is maintained (i.e. with the 
sea, or with the sea on the beam) so as to avoid heavy pitching. 
Stern trawlers are able to fish longer in bad weather than side 
trawlers because the crew is in safe and dry positions to oper- 
ate the gear. In respect of icing up, experience has shown 
better performance with stern trawlers due to shipping less 
spray and water because of the higher freeboard than with 
side trawlers where the freeing ports and the trawl winches 
ice up. Regarding seaworthiness, the stern trawler is as good, 
and perhaps even better, than a side trawler of the same size. 

What happens when the codend is completely full? This is 
still a problem, which probably arises only once a year. A 
catch of 25 tons has been brought on deck safely in severe 
weather conditions without creating undue problems, and 
it should be borne in mind that for 60 years fishermen have 
constantly been improving details of the gear of side trawlers. 
Stern trawlers at present operate with side trawling gear, but 
it is likely that this is not a good proposition. Stern trawlers 
should have their own gear which fishermen should start 
improving. 

Grass (owner of a stern trawler) found that in the rare cases 
when the net was full, the fore part had to be cut to release the 
weight 9 and if the net was on the deck, to get the catch out 
more easily. 

Hunter has said that transom stern trawlers have 20 per 
cent, higher resistance. Model tests, which have been made 
with stern trawlers, have been very encouraging and the 
resistance is found to be just slightly more than for ordinary 
side trawlers of the same size. The reason for Hunter's state- 
ment may be that a type of transom stern was used which was 
too deeply immersed in water and therefore not advantageous * 
at the speeds at which these ships operate. A cruiser stern 
would probably be slightly better but would never result in a 
20 per cent* difference. 

MR. G. S. MILNE (U.K.) agreed with Heinsohn that a stern 
trawler need not show much extra resistance over the tradi- 
tional cruiser stern trawlers. He felt however, that the 
principfe did not show to advantage for vessels below 180 ft. 
(55 m.) LBP operating in North Atlantic waters. 

MR. G. C. EDDIE (U.K.) suggested that the reason for any 
apparent difference in die quality of fish bet ween stem trawling 
and side trawling is that item trawlers are distant water 



trawlers making long voyages. The dominant factors are time 
and temperature; other factors, like the length of the death 
struggle and high pressure for a few minutes, were not impor- 
tant in this type of ship but might be of more importance in the 
smaller stern trawlers which have been suggested for the 
North-East Pacific. 

MR. F. MINOT (U.S.A.) believed that stern trawlers would 
develop greatly in the future and would prove their excep- 
tional seaworthiness. The question of the difference in 
resistance between a stern trawler and a cruiser stern side 
trawler did not seem to be due to the stern shape but rather 
to the ramp. 

MR. E. C. GOM>SWORTHY (U.K.) said that fish brought by 
stern trawlers could easily be more than eight days old. 
Fish meal would be the result unless distant fishing were done 
by factory ships. Recent developments had shown that side 
trawling was on the way out, and fishermen still being 
suspicious of the new method should be invited to come on 
board stern trawlers, to see for themselves that these vessels 
were as good as the side trawlers. Stern trawling most cer- 
tainly safeguarded the fisherman and made his life more 
comfortable. For these reasons alone it seemed inevitable 
that stern trawling would be the method of the future. The 
problem of pitching and heaving referred to by other partici- 
pants should be easy to deal with. 

MR. V. ESTEVE (Spain): It is no easy matter to decide which 
trawling method is best as regards ease of net handling, 
volume of catch and quality of fish. In Spain, all fishermen 
on the northern coast without exception trawl over the side 
of their ships, while most of those on the eastern coast trawl 
over the stern. The catch by either method is about the same 
and so is the quality of the fish. The boats from which trawl- 
ing is done over the side normally have gallows on either side. 
Those using the stern trawling system have large-diameter 
net rollers, a guide rollers or gallows depending on the 
shipmaster. Both types of ship use the same sort of winch. 

MR. L. SOUBLIN (France): His opinion was that the stern 
trawler factory ship is satisfactory from the technical stand- 
point, but that the principle is open to question. 

There is no reason to fear that the fish caught by stem 
trawlers is inferior in quality to that obtained by side trawling. 
On the contrary, the filleting and freezing of fish that have just 
been caught result in a high quality product. The trawl can 
be hauled in rapidly and efficiently in one operation. Trawling 
in bad weather is made much easier. The crew working on 
the lower deck is well protected in very comfortable conditions. 

These points, and many others, indicate that the stern 
factory trawlers are highly satisfactory from the technical 
standpoint. Nevertheless, they have three important require- 
ments with regard to: 

Weight (winch and various gear on the upper deck) 

Length (82 ft. or 25 m. clearance are required between 
the winch and the aftermost hatchway; hence at least 
100 ft or 30 m. between the winch and the after end of 
the ramp) 

Beam (because the deck admiahips must be cleared for 
shooting the trawl, it is necessary to provide for additional 
fish poods on each side to store fish temporarily) 

These three requirements necessitate very large trawlers. 
Thus, stem trawHng must be associated with very large 
factory trawlers. This very principle, he found, was open to 



[124] 



TRAWLING DISCUSSION 




Fig. 1/4. Proposed stem trawling arrangement without ramp 

question because some national fish markets cannot accept 
the large production from this type of ship. 

The stocks in the sea are not inexhaustible; for some species, 
they seem to be already decreasing. There is moreover real 
depletion, such as, for instance, the inordinate catching 
which should be frankly denounced and courageously dis- 
cussed of one- and two-year-old herrings in some coastal 
areas of the North Sea, which constitutes a veritable genocide. 
He feared that these large trawlers, in view of the need to 
fill their holds, will gradually go in for overfishing and thus 
contribute toward the progressive depletion of the resources 
of the sea. In this sense one can say that this type of ship, 
which is very satisfactory from the technical standpoint, is a 
design the principle behind which is open to question. 

MR. F. DORVILLE (France): Deep-sea trawlers are developing 
very rapidly and will in all probability evolve into self- 
contained factory ships. Important progress has been made 
with regard to hull construction, speed, and crew comfort. 
Electronic devices are increasingly used. Yet, on the other 
hand, means of handling the gear and the catch have changed 
but little over the past years. Means of hoisting the net are 
still missing on trawlers of the classical type. The present 
system, consisting of mast, derrick and fishing winch, cannot 
be considered as an efficient solution, in spite of the skilful 
use made of it by the fishermen. On new factory ships, 
derricks and winches have become more and more numerous, 
bringing about a real complication of gear. 
Fishing methods have been widely tested over a very long 



period, during which the basic principles underlying the 
methods have withstood any attempt at modification. This 
must not apply also for the future, especially in the case of the 
trawl, which, in spite of all recent improvements, must always 
be kept alongside the ship, borne by its own buoyancy, and 
emptied into the fish ponds on the deck to prevent damage. 

With the above ideas in mind, Mr. Dorville's firm, in 
association with fishing experts and with one well known 
winch maker, has developed a new way of operating the 
trawl from the stern of a large trawler by centralizing the 
mechanism for the gear operation at the aft end of the ship, 
though keeping the method of lifting the net now used in 
side fishing (fig. 114). 

The new stern trawling unit consists of a shroudless bipod 
mast and two symmetrically arranged groups of mechanism 
for shooting, controlling and handling the trawl. Each group 
consists of a revolving crane with 3 ton and 16 ft. (4.5 m) 
range, and an electric fishing winch with brake and warp- 
guiding gear. Two separate motors and control gears are 
provided for the operation of the associated winches and 
cranes. Elimination of the gallows system, with the warping 
fairleads and bollards, allows the warp to have direct way. 
A watertight steel folding flush hatch tightly covers the hatch 
space under the mast. It is fitted in a frame and forms a 
hinged ramp enabling the fish to slide easily and quickly to 
the 'tween-decks. 

Trawling operations are performed as follows: 

Shooting. The codend is picked up by one of the two 
revolving cranes, pulled back, lowered astern and dropped 
in the ship's wake. By its resistance in the water it pulls the 
whole trawl over the transverse roller on the bulwark into 
the water. After the bridles have been paid out from the 
winches the veering is stopped for unhooking the otter boards. 
Then the necessary amount of warps is paid out, the winches 
are braked, and trawling starts. 

Hauling. The warps are hauled in on the drums of the 
two winches, then the otter boards are hooked up, disen- 
gaged from warps and bridles, and the bridles hauled in the 
conventional way until the wings appear. The ends of the 
foot rope are then seized by one crane each, and in one single 
operation by .both cranes the whole trawl mouth is first raised 
and then lowered on to the deck at the aft end of the ship. 
The codend is then attached in the customary way and lifted 
by one crane, either over the stern if the catch is normal, or 
over the sheltered side of the ship if the catch is large, and is 
discharged into the hold by hauling over the hatch cover 
ramp. Thus the codend is hoisted directly from the sea and 
brought over the movable ramp without contacting either the 
hull or the deck, thus avoiding any damage to the fish or nets. 

The design of this stern trawling unit allows valuable 
deck space to be gained, owing to concentration of the gears 
aft, which enables the crew to work with increased safety on 
the whole deck area. The output increases, although there is a 
reduction in the number of the crew, and the whole operation 
is accelerated. All operations are mechanically controlled 
from the bridge. . 

Due to growing difficulties to find qualified crews for the 
very hard job of handling the gear on side fishing trawlers, 
the demand for rational mechanization is becoming more and 
more urgent The answer to this fundamental problem might 
be this stan trawkng unit with a remote control equipment. 



DR. J. SCHAHFE (FAG) : Dorvilk's 



is no 



progress in trawl hauling is not quite justified. Besides some 
small improvements oa conventional side trawlers, as, for 



[125] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



instance, the "bang up" method of dealing with tile heavy 
bobbin groundrope and the mechanical hoisting of the body 
of the net, there has also been the development of the British, 
Russian and German stern trawler* with chute. Their 
equipment for fully mechanized hoisting of the net, which is 
used on a commercial scale with satisfactory results is care- 
fully described and discussed in this book. 

The use of separate winches for each warp, which has 
already been considered in the past, should contribute to 
decreasing the wear on the warps and to increasing the safety 
of the crew working on deck. However, it seems that the price 
of such an arrangement as against that of the conventional 
trawl winch has acted as a deterrent to its introduction. 

Large super trawlers are now fishing in weather up to 
Beaufort 8 to 9. The operation of the proposed system with 
revolving cranes which, with only a 3 ton capacity, seem some- 
what small, might become difficult. The hoisting of a bag 
filled with about 3 tons of fish which is the common weight 
for a splitting bag" . . . without contacting either the hull 
or the deck . . ." would hardly be possible when the vessel is 
rolling and pitching in a rough sea. 

Deck space can certainly be gained by omitting a stern 
chute. But this factor is not of importance to ships with a 
'tween deck for processing the catch. It is not quite dear 
how the operation can be greatly accelerated with the pro- 
posed arrangement, particularly as the method of dealing with 
big catches (more than 3 tons) is not described. 

MR. Y. TAKAHASHI (Japan): The first Japanese commercial 
stern trawler of 1,500 gross tons, 1,800 h.p. was built in 1958. 
This boat is a combination freezer vessel. The length of the 
slipway, or stern chute, is too short. Operating results have 
not been altogether successful, mainly because of the long 
time needed for lifting the net, and there is some belief that a 
side trawler might be better. The defect mentioned might be 
overcome by lengthening tip distance between the chute and 
the winch. Another weak point of this boat is the square 
stern which often causes entanglement of the net. Round 
sterns only will be built in the future. 

With regard to the trawl winch power, this in Japan is 
usually from 60 to 90 h.p., but in France it is almost 120 h.p. 
and in some other countries it is as high as 200 to 250 h.p. 
It would be much appreciated if an explanation could be 
given for these big differences. Incidentally, Japanese trawlers 
are operating to depths of 2,000 ft. (800 m.). 

MR. L. M. HARPER Gow (U.K.): He spoke as a ship manager 
and not as a technician of his experience since 1953. At that 
time, they had carried out some experiments with the Fairfrec 
to investigate possibilities of stern trawling and freezing at sea, 
At the time they had under construction the Fair try, which 
started operating in 1954. 

Fairtry I completed 18 operational trips in 4i years (4 trips 
per year) which was approximately what was planned. In 
1955 and 1956, the last being a particularly good year for 
distant-water fishing, the results were satisfactory enough to 
make them decide to construct two more vessels, following the 
lines of Fairtry /, but with such improvements as found 
necessary and advisable. See fig. 115 fot the general arranp- 
ment drawings of Fairtry // and ///. The main controversial 
points of this type of vessel are: 1. Stern trawling; 2. Produc- 
tion at sea; 3. Personnel problems. 

1. There was little change in general design in the two new 
vessels. They had improved the layout in design to allow the 



gear to How mote freely and come to more easily , and altered 
the arrangement to prevent the danger of the trawl net coming 
into the propeller. There is a danger in the first vessel, but h 
has only happened once. On that occasion the vessel nearly 
had to call for a salvage vessel but die managed to dear it 
herself. The Russians have _ probably had the same experience 
in heavy seas with strong winds. 

In 18 voyages the gear had been shot about 10,000 times. 
Therefore it would be dear that the crew would not continue 
to do this unless it went smoothly. It could therefore be said 
that this is no longer an experimental method of handling 
trawling gear but a perfectly normal one. It is not the only 
method but it happens to suit the large factory trawlers with a 
'tween deck. 

2. He wanted to discuss the question of production at sea 
later (see Part IV -discussion). 

3. Regarding the personnel problem, which occurred in 
many places, particularly among the Americans, he did not 
feel that any troubles were present, although it was anticipated 
by the trawler industry and might have turned out very 
differently if they had not had the full support of the trade 
unions and the services of a somewhat outstanding skipper 
who was able in the early days to hold the crew together. 
He admitted that in the first two or three voyages, it was a 
difficult problem to get the men accustomed to remaining at 
sea for two to three months. That difficulty had largely been 
overcome. They could have attracted men from the start by 
very high rates of earnings, but obviously with a crew of 
80 men or more, they wished to keep the earnings on a fair 
basis, not an extravagant one, and they tried to increase their 
earnings by increasing production. The crew receive at least 
50 per cent, of their earnings on production and therefore if 
one can get them to increase the production or the value of it, 
the pay automatically improves. There is probably some 
room in Britain for further increase in pay, should that be 
necessary. Earnings still were below those of the deep-sea 
trawlers working out of Humber. 

Reverting to stem trawling, he agreed that the problem of 
getting a heavy catch up the slip does exist, and that methods 
had to be improved to overcome this problem. The problem 
is however in acceptable proportions. The amount of fish lost 
by the odd heavy bag brought up the slip is very low in relation 
to the total catch. 

He firmly believed that this type of vessel would increase 
and develop. It has been proved to work in a practical way 
and it is a logical way of utilizing the catch fully. It would 
take a long time, and he doubted whether factory vessels 
would ever do more than supplement the normal standard 
fishing vessel. 



MR. H. HENSOHN (Germany): He made some explanatory 
comments on the horsepower of the trawl winches used on 
stern trawlers. He is using basically the same type of winch 
as is used on side trawlen and he had found that the output f o r 
the trawl winch has something to do with the output of the 
main engine. According to the experience of the German and 
British skippers, the fine is at f^ 
the intention being to haul the net up quickly. There might 
be some sound reason behind this, but what matters in his 
opinion is the speed of the net through the water, which is a 
result of the ship's speed and the hauling speed. Now if the 
ship's speed is increased the pull on the winch must be much 
heavier than if the speed is reduced, so for trawlers with a 
high horsepower with engines running full speed ahead one 



1126] 



TRAWLING DISCUSSION 



must have a much stronger trawl winch. He has tried to 
explain to skippers that what matters is the speed of the net 
through the water and that if they reduce the speed of the 
vessel the speed of die trawl winch goes up simultaneously. 
Regarding the output, the first trawler had 180 h.p. and the 



power gradually was increased to 250. The tendency now is to 
go up to 300 h.p. or more. 

MR. A. HUNTEH (U.K.): He supported Hetnsohn's remarks 
about trawl winches. It appeared from the methods employed 




MAIN DECK 




LOWER DCOC 



Fig. 115. General arrangement of Fairtry II end III 
[127] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



by tome skipper* as if the trawl winch should ha ve the same 
power as the main engine so thai they could fight it out 
British ships with 1,500 to 1,700 tup. engines usually have 
winch motors of 300 h.p. The normal trawling speed is 
3| knots and the winch can haul from the mean barrel position 
at roughly the same speed, viz: 250 ft. (75 m.) per minute. 
It was therefore difficult to understand why when the order 
for hauling up the net is given the main engine telegraph 
should immediately be rung to "Full speed ahead" as is 
sometimes done* It is understandable that the gear should 
lift off the bottom quickly, but surely in the end it is the 
question of the speed through the water which counts in 
preventing die fish escaping from the net, 

There seems great room for education in this matter. The 
trawl winch with its actuating machinery is an expensive item 
of equipment in a large trawler and the whole success of the 
voyage depends upon it Yet when the trawl gear is shot 
these mechanisms axe subject to the most primitive usage. 




Fig. 116, Stern view of a trawler rigged with a drum for handling the 

net 

Sometimes when shooting the ship steams at 6 to 8 knots and 
the warps are paid out with the winch brakes almost full on 
with sparks flying all over the place. There would appear to 
be room for improvement in practice and perhaps also in 
design. 

MR. H. KRISTJONSSON (FAO): Heinsohn and Hunter have 
mentioned the habit of trawler skippers of increasing towing 
speed when beginning to haul up the trawl and it sometimes 
calls for rather critical power requirements, and the question 
was posed: "Why do the skippers do this, and is it necessary to 
increase the towing speed so much at this point?" Obviously 
the need for accelerating the towing speed when beginning to 
haul up depends largely on the species fished, how fast swim-^ 
ming and active they are, the trawling speed of the vessel prior* 
to hauling, the construction of the net, etc. In many fisheries 
there is, of course, no such speeding up at the beginning of 
hauling. On the contrary, it is common practice, for instance 
in die Mediterranean, to leave the net practically stationary 
cm the bottom, the vessel coasting backwards while hauling in 
the warps, in some Scandinavian fisheries the vessel even 
doubles on its track, steaming towards the net while hauling in 
die warps* 

The fact remains, however, that under certain conditions it 
te essential to increase the hauling speed when beginning to 
haul up. Mr. Kristfonsson thought that perhaps the most 
convincing proof would be found through underwater tele- 
vision observations, such as those started some years ago by 



the U.S. Fish and Wildlife Service. A most interring film 
taken by an underwater camera placed in the codend of a 
trawl, first facing aft and later facing forward, was shown in 
1957 at the FAO International Fishing Gear Congress in 
Hamburg. At that tune underwater research on the behaviour 
of fish in front of and inside a trawl had not quite reached a 
conclusive stage, yet it was fascinating to watch the fish swim 
just in front of the footrope sometimes for a considerable 
time then maybe relax and be carried aft into the belly, 
feeling themselves trapped when coming into the codend 
and then perhaps trying to escape out of the mouth of the net. 



Smaller stern trawlers 

MESSRS. DAYTON L. ALVERSON and PETER G. SCHMIDT JR. 
(U.$A.): Purse seiner type vessels ranging from about 50 to 
75 ft. (15.2 to 22.8 m.) in length constitute the bulk of fishing 
craft trawling from Puget Sound, Washington, U.S.A. ports. 
A typical multi-purpose vessel of this type was described by 
Hanson (1955). Combination purse seiners have become 
popular because of their versatility in other fisheries, such as 
salmon and herring seining, tuna trolling, and gillnetting. 
When rigged for trawling, either of two types of winches are 
used to handle the trawl warp. The centre winch, which 
houses both drums in one unit, leads toward the guard rail 
and the wire is led around heavy blocks aft to the davits. 
Divided single-drum winches with a common drive shaft are 
also extensively used. These are set to feed directly aft to the 
davits. 

As Pacific trawlers employ relatively small crews, say 3 to 5, 
handling the net is facilitated by hauling in the wings, body, 
intermediate and codend of the net in successive lifts, using 
the boom and winch. This method is relatively safe during 
average weather conditions as no bobbins are used, but not 
in squalls when it may result in loss of fishing time. This 
handicap has been partially overcome with the advent of the 
drum trawler shown in fig. 116. These vessels (Alverson, 
1959) are fitted with power drums to haul in the wings and 
body of the trawl. Successive lifts of the net are not necessary 
as only the codend is lifted aboard. 

Although small boats have generally been satisfactory for 
most coastal fishing, they have some disadvantages for Puget 
Sound trawling. These vessels generally make longer trips 
than those operating from coastal ports. The expansion of the 
fishery to northern Vancouver Island and Hecate Strait, 
British Columbia, has resulted in trips averaging from 8 to 
11 days each and runs up to 500 miles. Fishing in Hecate 
Strait has been possible because increased yield per fishing 
effort has exceeded increased operating costs. The small size 
and relatively small capacity of these vessels, coupled with 
slow sailing speeds of about 9 knots have, however, reduced 
their ability to obtain maximum benefits from the more 
productive distant grounds, 

A factor which may further reduce their effectiveness is the 
recent development of territorial rights. Territorial extension 
would exclude Puget Sound trawlers from fishing grounds 
from which a large percentage of their catch is currently 
derived. 

To compensate for the loss of such areas, fishing vessels 
would either have to intensify exploitation of the species in 
the deeper waters along the outer continental shelf or to fish 
further afield perhaps in the Gulf of Alaska, where some 
large unexptoited banks exist between Cape Spencer and 
Kodiak Iffoml. AMwMig* 1 the tmfl%r vessels now fishing 
in the Pacific Northeast would be suitable, but perhap not 



1128] 



TRAWLING DISCUSSION 




HOLD PLAN 



Fig. 1/7. Proposed 84 ft. (23.6 m.) stern chute trawler 



[129] 



FISHING BOATS OF THE WORLD : 2 TACTICS 






Fig. US. Proposed 127ft. (3S.8 m.) shelter deck stern trawler (see also overleaf) 



efficient in the deeper waters, they would not be capable of 
distant trawling in the Gulf of Alaska. 

Two trawler designs should be considered: (1) a vessel 
capable of operating efficiently in grounds currently fished, 
and (2) one able to trawl in the Gulf of Alaska and the Bering 
Sea. If future trawling leads to greater offshore operation, 
the "sea-ability" and ability to fish in relatively rough seas 
will be of considerable importance. For the local fishery, 
alteration of deck design and equipment may be sufficient. 
It would be advisable to utilize the drum trawl and stern 
chute. This method could be improved by shifting the drum 
forward, which would aid in handling the net and would 
avoid, in most instances, having to lift the heavy codeod over 



theside. With a larger vessel a shelter deck could be provided. 
Drawings of an 84 ft. (25 . 5 m.) combination trawler for the 
local Pacific Northeast fishery are given in fig. 117. Major 
departures from die current seiner-trawler include an offset 
deckhouse, a stem ramp, and a combination offset trawl 
winch. The deck plan offers a number of advantages: (1) the 
offset deckhouse provides extmnely good visibility from the 
pilot house (approximately 315) which allows the skipper to 
observe the handling of fishing tear on deck, (2) the winch 
operator, protected by the raised forecastle, can see the trawl 
warps at all times* (3) a large dear work ana is available, 
(4) a hydrauJkalry controlled boom or crane is free to swing 
300, and (5) the stem ramp and drum winch combination 



[130J 



TRAWLING DISCUSSION 




HOLD PLAN 



Fig. 118 continued 



brings the codend aboard in two hauls. If "splitting" is 
necessary this can be done in the normal way. The advantages 
of the stern chute trawler have been discussed by Birkhoff 
(1959). 

The hold is designed to provide ice storage with auxiliary 
refrigeration, or to contain chilled seawater. The vessel has 
an estimated fish capacity of 120,000 Ib. (54.5 ton) of iced 
fish or 129,000 Ib. (58.5 ton) offish carried in chilled seawater. 

The vessel can be easily converted for purse seining or for 
kmgUning. In addition to bottom trawling, the vessel can be 
used in the Alaska king crab or shrimp fisheries. 

This smaller trawler is proposed for operation in areas from 
the Columbia River to Northern Hecate Strait. Maximum 
running distance would not exceed 500 mites, although the 
operational capabilities are much greater. South-east storms 
are frequent in these waters for much of the year and small 
trawlers lose dose to 3 5 per cent, of the available fishing time 
because of advene weather. The stern chute should allow 
fishing in relatively heavy seat. If one additional fishing day 
per trip could be attained, the average catch per trip could be 
increased 15 to 20 per cent. Reduction in hauling and totting 
lime should also add to the general fishing efficiency. 



The main details are: 

LOA . 

B, moulded . 

D, moulded . 

GT . 

Hold capacity 

Fuel oil capacity 

Freshwater capacity 

Engine output 

Approximate speed (light) 

Approximate range 

Plans for a 127 ft. (38.8 m.) medium-distance trawler are 
shown in fig. 118. As witfc the smaller vessel, an offset house, 
stern chute, and forward-placed drum winch are suggested. 
The advantages of this arrangement are similar to thoae 
given for the smaller boat. The added length allows for 
bringing the net aboard in one haul. In addition, a shelter 
deck is provided to handle or process the catch. Processing 
equipment, if desired, can be installed on the shelter deck. 
The catch is hauled to the work deck, sptlted throutfi a loading 
hatch, separated into fish bios, and then loaded into the fish 
hold. Doors are provided on the side shelter deck for fast 



84 ft. (25.6 m.) 
23 ft. (7.01 m.) 
12 ft (3.66m.) 
146 

90 ton at 40 cu. ft/ton 
25 ton 
3 ton 

360 h.p. at 375 r.p.m. 
10} knots 
4,000 mites 



I 



[131] 



FISHING BOATS OF THE WORLD : 2 TACTICS 



If dock fscQities aw not adequate for handling 
hutch ^11*1 bo used* Hold 



capacity is about 400,000 Ib. 0*5 ton) for iced fish and 
430,000 Ib. (200 too) when carried in chilled seawater, 

The vessel also can be used in the purse seine fisheries for 
herring, sardines, or tuna, as well as for king crab or 
dhrtmp. 

This suggested trawler could fish all the present areas, as 



the incentive to initiate trawling on the more distant 
grounds. 

The main details are: 

LOA .... 

B, moulded . 

D, moulded . 

GT . 

Hold capacity 



127 ft. (38.8 m.) 

30ft. (9.15m.) 

14 ft (4.2? m.) 
500 
250 ton at 40 cu. ft./ton 





Fig. 119. 32ft. (9.75 m.) multi-purpose fitting boat with layout for trawling 



well as the extensive Gulf of Alaska banks. Maximum operat- 
ing range without processing equipment would be about 
1,400 miles. Operating conditions would be more severe 
than those encountered on present grounds, as gales are 
common during a large part of the year. The large "stagfe- 
hauT through the stern chute would improve the fishing 
abffity, and the shelter deck would provide protection for die 
trawl grounds of the Gulf ha ve been reported to 
am large ccKrtratk>t of unfls^ 



Hmfliir to the red-fob of the Atlantic, which ihoukl provide 
high yttdi for dfctonttrawfco. The growth of future mark**, 
oouptodwtth possible cbaoga to territorial MU, could provide 



Fuel oil capacity . 
Freshwater capacity 
Engine output 
Approximate speed (titftt) 
Approximate range 



115 ton 

14 ton 
800 h.p. at 310 r.p.m. 

12* knots 
8,000 miles 



ME. A. HUNTS* (U.K.): In the smaller size of stern trawlers 
such a* proposed by Ahwson, he asked if sufficient experi- 
ence had tarn gabled regarding the safety of the stern ramp 
arrangement in a following sea. There could be conditions 
where the set could flood the deck by coining up die ramp. 
It was noticeable that this design considerably restricted tte 



{132} 



THAWLINO DISCUSSION 



accommodation and the arrangements shown by 
Alvenon would not be acceptable in Britain where the 
staving accommodation hat to be placed at toast 5 per ant. 
of the ship's length abaft the forward perpendicular. Mora- 
over three beds in the height would not comply with British 
law. Care also would be required in balancing athwartship 
weights without undue weight of compensating ballast always 
more difficult in the smaller ship. 

Ma. D. L. ALVERSON (U.S.A.): There is no restriction in 
crew's quarters in Schmidt 1 * and his design. On purse 
seiner type vessels the crew is always put up in restricted 
quarters far forward, in the U.S.A. they do not have to put 
up with the regulation mentioned by Hunter. He is of the 
opinion that the broad stern is no problem, not even in a 
following sea. 

Recruitment of fishermen is very difficult and hence as much 
as possible should be done to improve working and living 
conditions on board the ships. In the U.S.A., in line fishing, 
the average age of the fishermen is over fifty years. The 
trawling fleet shows a somewhat lower average age which 
might be due to the shorter trips these trawlers undertake. 

MR. P. GURTNER (FAO) mentioned that stern trawling had 
been introduced in India for some time now even for very 
small boats ranging from 25 to 32 ft. (7.5 to 9.75 m.). The 
smaller boats do not normally have a winch, but the net is 
hauled by hand and towed from one or two samson posts at 
the extreme aft end. Bigger boats are now generally rigged as 
shown in fig. 1 19. Some criticism was heard from fishermen 
against having trawl davits at the extreme aft end of the boat, 
when bad manoeuvrability was experienced. Trawl davits 
are now fitted about i LOA forward of the transom and 
much improved manoeuvrability is expected. Fig. 119 shows 
a 32 ft. (9.75 m.) trawler. 

Future development 

MR. H. KRKTJONSSON (FAO): It must be regretted that the 
discussion on stern trawling had dwelt too exclusively on 
trawling over a ramp or stern chute, while little mention had 
been made of the old and conventional stem trawling arrange- 
ments, such as the Mediterranean one, where there is certainly 
also scope for improvement. On Mediterranean trawl boats 
it is customary to place the winch rather far forward so that 
fewer strapping operations are needed when taking in the net. 
This method could, however, be further improved, but the 
main question is: Is it practical to take on board such light- 
weight trawl nets as the Mediterranean ones with their small 
catches, or can time and labour be saved by adopting the mode 
of operation used in the Gulf of Mexico shrimp fishing and on 
some stem trawlers on the U.S. West Coast, where the stern 
of the vessel is swung around slightly to bring the codend up 
to the side, leaving wings and belly in the sea? This is one 
example of the scope of efficiency studies which are urgently 
needed on board fishing vessels. But such work studies must 
not be limited to finding out how to save labour in the hand- 
ling of the vessel and gear, but should also cover handling 
of the catch. For instance, the small Mediterranean trawl 
boatscany crews of six to nine men not mainly for handling 
the fear but for sorting the small species in the catch meti- 
culously into little bows for icing. Similarly, up to 40 people 
mre sometimes carried on Icelandic long-distance trawlers, 
mainly for gutting the fish when working on exceptionally rich 
grounds, 



The big problem of saving manpower is federally 
doeely tied up wilh handling ai* 

board* Factory ships staying at sea for a couple of months,, 
operating in distant grounds more than 1,000 miles from Ike 
home port, are obliged to cany large crews and complicated 
machinery for processing die fish. Such elaboration of the 
catch at sea is inherently expensive. On vessels staying out 
for a shorter time, Le., less than 20 days after q**^*g the 
first fish, there is bound to be an increasing trend to save labour 
by minimizing elaboration of die catch and streamline this, 
through mechanical handling and automation to be able to 
operate with very small crews. Provided with gc*>d accommo- 
dation and labour easing, as well as labour saving appliances, 
the crew members should work long hours white at sea and 
rather enjoy their leisure time at home by staying on shore 
once in a while by rotation. This would make fishing a mote 
attractive employment. 

An ideal fishing boat would then resemble a tanker where 
the fish is dumped into a tank with chilled brine or sea water, 
or preserved by other simple means where laborious gm*iqg 
bleeding, and other handling is avoided. Mr. Kristjoosson 
was curious to hear the opinion of die fish processing people 
about such possibilities. He was afraid that research oa 
keeping fresh fish in chilled brine or sea water so far had beea 
done mainly in countries which fish in cold waters where was 
relatively little difference between the chilling temperatures 
and the temperature at which the fish live and also the 
bacteria on the fish. This method of preserving fish in fresh, 
condition is, however, much more hopeful when fishing in 
warm waters where there is a drop of maybe 35 to 55 F 
(20 to 30 C.) from the sea temperature down to chilling: 
temperatures. Such drastic chilling of the fish immediately 
when it comes out of the sea should effectively arrest spoilage 
and might quite likely result in improved quality and increased 
keeping time with an absolute minimum of handling. 

Progress in this direction would obviously have a very pro* 
found effect on fishing vessel design and on the economics of 
fishing operations, as drastic savings might be achieved in 
labour which is universally and increasingly the biggest cost 
item in fish production. 

PROFESSOR A. VON BRANDT (Germany) : Most of the discussion 
was concentrated on stern versus side trawling, their advan* 
tages and disadvantages, fish quality problems and crew 
problems. It seems to him these questions were answered as 
far as it was possible. There was only one question regarding; 
the gear itself: should a new type of gear for stem trawling be 
developed. 

Knowledge of the conventional types of trawls is still 
restricted. For gear research, not the bottom trawl but the 
floating trawl is now in the centre of attention. It seems 
necessary to say that in future there will have to be more 
interest in floating trawls in connection with biological and 
economical problems. This could influence the deck arrange- 
ments a great deal and naval architects should watch this 
development carefully.' 

Coau&aad of operation 

MR. J-O. TRAUNO (FAO, Rapporteur): Two reasons have 

prompted the subject: 

To transmit the intentions of the skipper as fast as. 
possible 

To transmit die brain impulses at the skipper to th* 
react ion of the vessel 



1133] 



PISHING BOATS OF THE WORLD * 2 TACTICS 



Hardy and Pain have attempted the task of putting forth 
their idea* no the subject. Sttberkrflb's, Chardome's and 
Hfltaoiuft papers alto deal with this sutgect Hrinsohn's 
paper gives a very vivid account of what is possible for a 
skipper from the bridge of a modern vessel. 

ME. G. C. EDWE (U.K.): The concept of the flight deck of an 
aeroplane in the bridge of a modern fishing boat is not a 
<x>rrcct one. The skipper's automatic navigator is to be placed 
At one end of the bridge and the echo-sounder at the other end, 
o that die skipper gets enough exercise and is relieved of his 
mental anxiety which is very often the cause of mishaps. 

He doubled the extent to which automation could be carried 
out in a fishing boat Such centralization tends to increase the 
anxiety and strain on the skipper and he would recommend 
that the equipment on the bridge be restricted to what is 
absolutely necessary. As automation is the rule of the day, 
it has to be accepted. 

MR. . C GOLDSWORTHY (U.K.) : If one cannot get the trawler 
skipper to think in terms of a speed of 2J or 3| knots in con- 
ducting his fishing operations, he wondered bow it is possible 
to make him understand anything else in fishing. It is a 
question of education. It is problematical if the advent of 
gyro compass, echo sounders, radar and all modern equipment 
has brought about any additional safety. 

However, the fishermen have the equipment and they tend 
to grow more and more automation minded. 

MR. H. HONSOHN (Germany) said that a feature of modern 
German trawlers is a revolving chair for the skipper on the 
starboard side, around which the naval architect has arranged 
various devices. The arrangements shown in Hardy's and 
Pain's drawings would not be favoured because of the 
absence of the revolving chair 

Due to lade of space, the radar screen or screens are nor- 
mally arranged on the port side. In the starboard bridge wing 
is a second helm control and the engine telegraph and/or 
propeller bridge control, which should be within reach of the 
skipper from his revolving chair. 

In certain vessels some controls are purposely put out of 
reach of the skipper's chair, so that another person must also 
remain on the bridge. Automation means that the man may 
be in sole control, which is against German law and there is a 
consequent risk of mishaps, 

CAPTAIN P. F. EDGE (U.K.) said that white fitting out a new 
ship, he found it rather difficult to place all the gadgets. He 
noted that old skippers tended to find all these gadgets in (he 
wheefhouse very disturbing, but in the case of younger skippers 
acquainted with automation and electronics, great benefits 
might result from centralized control positions. 



MR. A. HUNTBR (U,K.) quoted the old Navy saying "Though 
the instrument may be perfect there are limitations to the 
man". He bit that these proposals rather reversed this. 
Whfle the proposals were imaginative they perhaps tended to 
imitate too much the control of a modern aircraft. Full 
reliability of rudder control was essential, and the function 
of the steering gear was not only to control the rudder angle 
but also to hold the ship against the action of the sea. Robust 
steering gear was therefore essential. Visibility forward and 
aft is of the utmost importance to the trawler skipper, and 
the size of the control console proposed would prevent access 
to some of the wheelhouse windows. Moreover, such controls 
had to take into account the activities of the skipper when 
fishing. These operations enforced quick action between the 
doors at the bridge wings, a weather eye forward and a quick 
use of engine and steering controls. It was hardly likely he 
would respond readily to delegating some of these responsi- 
bilities to a dose television circuit 

MR. DWK3HT S. SIMPSON (U.S.A.) agreed with Hardy and 
Pain and said that there were two main requirements for 
successful centralized control a pilot house from which the 
skipper could see all the ship operations without going outside, 
and a diesel equipped engine room. Perhaps a third should be 
mentioned a well trained skipper. 

He believed that the starting of the engine should be 
omitted from the pilot house and left to the engineer, who 
could see what he was doing. Probably this also applied to the 
manoeuvring of a reversing engine, although in the smaller 
engines that can be easily arranged for the pilot house too. 
These installations would pay for themselves by releasing the 
engineer for maintenance work. 

COMMANDER H. . H. PAIN (U.K.) agreed with Hunter as to 
the aids necessary for navigation. He however added that 
nothing could replace the need for good seamanship. 

An arrangement which would cut off fuel oil supply in case 
of over-heating of the engine was feasible and desirable. 
He would not suggest an elaborate system but would prefer the 
very flexible system of electric steering control of the con- 
ventional electro-hydraulic steering engine. 

The problem of older skippers who were not accustomed to 
automation would eventually disappear. The skippers of the 
future would be better educated and well versed in handling 
the equipment. The proposals might appear to be looking 
too much into the future, but most of the things which had 
been suggested were already in use in one way or another in 
many fishing boats. 

He suggested that the analogy of the flight deck of an 
aeroplane and the bridge of a modern fishing vessel was 
valid. Centralized control aims at increasing the efficiency of 
the vessel as a fish catching machine, at reducing the burden 
of the skipper thereby and also at reducing hazards and 
increasing safety. 



1134] 



STEEL AND WOOD SCANTLING TABLES (West Coast of UJS.A*) 

by 
H. C HANSON 

Figure* and scantling tables are given for small fishing vessels not covered by bodies such as Lloyds and the American Bureau of 
Shipping They are for wooden boats of from 30 to 90 ft. (9.15 to 27.4 m.) with bent-frame construction and for those of from 30 to 125 ft. 
(9.15 to 38.1 m^ with i sawn frames. They also cover V-bottom wooden boats of from 30 to 90 ft. (9.15 to 274 m.) and welded steel vessels, 
of from 30 to 130ft. (9.15 to 39.6m.) in length overall. 

TABLES D'ECHANTILLONS POUR L'ACIER ET LE BOIS (COTE OCCIDENTALS DES E.-U.) 

L'auteur donne des figures et des tableaux d'fchantillons pour des petits navires de pcchc n'fcant pas oouverts par des organisme* 
teh one fe Lloyds et PAmencan Bureau of Shipping. Us sont destines aux navires de bois de 304 90 pi. (9,15 4 27.4 m.) construits avec des 
membnires courbfes et aux navires de 30 4 125 pi. (9,15 4 38,1 m.) 4 membnnes scttes. Us couvrent autti les navires de bois 4 fond en V de 
30 4 90 pi. et les navires d'acier soudcs de 30 4 130 pi. (9,15 4 39,6 m.) de longueur tors-tout. 

TABLAS DE ESCANTILLONES PARA EL ACERO Y LA MADERA (COSTA OCCIDENTAL DE LOS E.U.A.) 

Elautor da figure* y tablas de escantilkmes para los pequeftos barcos de pesca que no est4naseg^radosporoifanizacionesccMno la 
LJoydt y el American Bureau of Shipping. Se destinan a los barcos de madera de 30 a 90 pies (9,15 a 27,4 m.) de eJora constniidos con 
cuadernasasenadas. Tambien comprende los barcos de madera de fondo enVde30a90piesyk barcos de acero soldado de 30 a 130 pie 
(9,15a39,6m.)deesloratotal. 



VIEWS were expressed at FAO's Fishing Boat 
Congress in 1953 that there was a need for 
information on scantlings for smaller vessels not 
covered by bodies such as Lloyds and the American 
Bureau of Shipping (ABS). The author has collected 
data pertaining to such types built on the West Coast of 
the U.S.A. for both wood and steel fishing boats. 

Wooden construction 

Bent frames comprise 90 per cent, of wooden boat con- 
struction. Fig. 120 to 124 show typical sections and 
some profiles of boats built on this system. Table 20 
recommends scantlings which represent common practice 
for vessels of bent-frame construction. The bent-frame 
in this case is white oak, if obtainable. This material has 
now become very scarce, so red oak, while it is not the 
best, is used to a large extent. It is not, however, very rot 
resistant, and to give it a reasonable life, it is cut to the 
proper sixes, the edges rounded slightly and then pressure- 
treated with preservative. 

Typical bent-frame boats have keelsons and keel 
bolted together, the frame is dapped into the keelsons, 
with hard-wood floors over the keelsons and frame, the 
frame, backbone and floors all being well bolted to- 
gether. In smaller vessels, such as beach seiners and gill- 
netters, deep floors we wed instead of keelsons, thus 
differing from the midship section shown. 



Sawn-frame construction is not used to any great 
extent nowadays, but boats so built range from 80 to 
125 ft. (24 to 38 m.) and are used for tuna fishing, but 
they are expensive to build due to high wages and lack of 
skilled shipwrights. Table 21 gives scantlings proved by 
practice. The midship section and profile, fig. 125 and 126, 
is of an 80x22 ft. (24.4x6.7 m.) wooden sawn-frame 
round-bottom combination vessel used primarily for tuna 
fishing, this particular one in Africa. 

The midship section shows two types of construction. 
The one to the left is a development from the bent-frame 
construction with single keel and keelsons bolted 
together forming an integral backbone. The framing can 
be sound if done properly by tenoning the cants into the 
keelson for about i in. (12.7 mm.); by having solid deep 
floors bolted to each frame as it is set, and with the floor 
sided to within 1 in. (25 mm.) of the width of the bay; 
and by filling the anchor stock floor over the top of the 
frame to the depth of the 'floor itself; all beiixg well 
fastened. Failure to follow this method of construction 
could lead to disaster if the vessel sustains any heavy- 
blow. 

Table 22 shows the scantlings for V-bottom vessels 
up to 90 ft. (27.4 m.) in length and it is baaed upon 
common usage for a great many years. The fishermen on 
the U.S. West Coast had an aversion to using V-bottom 
types, probably because they have been able to afford 



[137] 



FISHING BOATS OF THE WOULD: 2 CONSTRUCTION 




fig. 130. Bent-frame construction of U.S. West Coast oak boats 





Fig. 123. Wood beach seiner* 45 x 14J ft. (13 J2 x 4.42 m.) with 
4ft. (1.22m.) draught 




fig. 121. Wood constructed combination vessel, 44 J x 14 ft. (13.6 x 
4.3m.). Suitable 165 h.p. 



Fig. 124. 67x77x9.5 ft. (20.4x5.2x2,9 m.) combination boat 
designed for seining, otter trawling and trolling 





Fig. 122. Wooden setoer, 38x12 ft. (lit* 3.63m) with! ft. (0.91 1*.) Fig, 125. Midship section showing sawn-Jramc construction of 



i seiner, 38xl2ft.(n 



vessel ofaOx 22 fc 04.4x4.7 m.) 



1138J 



SCANTLINGS U.S. WEST COAST STEEL AND WOOD PRACTICES 



TABU 20 



LOA 



Stem (Hdwd.) 
Stem post (Hdwd.) 

Keelson 
Sister Keelson 
Fkx>rs (white oik) . 



ft 
m. 



Deadwoods . 
Shalt logs . 
Horn timber . 

Gripe (Hdwd.) 
Frames (white oak) 
Frame spacing 
After cants (S.W.) . 

Beams, sided 
Beams, moulded 
Beam spacing 

Bilge stringers 
Number of strakes 

Clamp, main deck . 
Shelf, main deck . 
Ceiling, main deck . 

Clamp, raised deck 
Shelf, raised deck . 
Ceiling, raised deck 

Garboard 
Sheer strake . 
Planking 
Broad strake . 

Guard (Hdwd.) . 

Sponson 

Shoe (Hdwd.) 

Decking 
Waterway 

Rim timbers 
Quickwork . 

Sag in keel . 



in. 
in. 
in. 



in. 
in. 



30 
9.1 



in. 6x8 

in. 6 

in. 6 

in. 8x8 

in. 6x6 

in. 2x3 



Floor* in place of keelsons 
(Hdwd.) . . . . 2x8 



in. 8 

in. 8 

in. 8 

in. 8 

in. 14x2 

in. 9 and 10 

in. 2Dbl. 



3 to 6 

3 

18 



in. 2x6 

. 4 

in. 2x6 

in. 2x6 

in. 1 (n) 

in. 2x6 

in. 2x6 

in. 1 (n) 

in. 14 (n) 

in. 1 (n) 

in. l(n) 

in. li 

in. 2x3 

. None 

in. li 



14x2 
14x6 



in. - 
in. 



45 
13.7 

8x8 

8 

8x12 

8X10 

8x8 

2x3 



3x8 

8 

10x12 

12 

8 

2x24 
10 
3Dbl. 

4 tog 

It 

3x6 
5 

3x8 
3x8 
li 

3x8 
3x6 
U 

2x10 
2x10 

lix^O 

2x6 
2x8 
li 

2x3 
2x12 

8 
4 



Afld 

50 

15.2 

8x8 

8 

8x12 

12x12 
8x8 
2x3 



3x9 

8 

10x12 

12 

8 

2x3 
10 
3Dbl. 

4to8 

34 
24 

3x6 
5 

3x8 

3x10 

14 

3x8 
3x6 
1* 

2x12 
2x10 



off the US. 
i gltca rtMb Ml to be 



CM* to M It (27.4 a.) 



14x10 

2x8 
3x8 
2 

2x3 
2x12 

10 
4 

i 



57 
17.4 

10x10 

10 

10X16 

14x14 
8x8 
3x4 



3x10 

10 

12x12 

12 

10 



3Dbl. 
44 to 94 
24 

3x6 
6 

3x10 

3x12 
2 

3x12 
2x12 
2 



2 
24 



2x4 
2x12 

12 
6 

1 



65 
19.8 

12x12 

12 

12x16 

14x14 
8x8 
3x4 



4x12 

12 
14 
14 

12 

3x4 
12 
4Dbl. 



5} to 

27 

4x6 
6 

3x12 
3x12 
2 

3x12 
2x12 
2 

1* 

2 



2 

4x12 

2 

2x4 
2x12 

12 
6 

1* 



10 



75 
22.9 

12x12 

12 

14x18 

14X14 
10x10 

4x4 



4x12 

12 
16 
14 

12 

3x4 
12 
4Dbl. 

54 to 12 



4x8 
7 

4x12 
3x12 
2 

3x12 
3x12 
2 



2 

4x12 

2 

24x4 
24x12 

12 
6 

U 



85 
25.9 

12x14 

12 

14 

14x14 
10x14 

4x4 



44x14 

12 
16 
16 

12 

Hx4 
12 
4iDbL 

5J to 12 

27 

4x8 
8 

4x12 
4x12 

2 

3x12 
3x12 
2 

3 
2* 

ii 

2 

5x12 

24 

24x4 
24x12 

12 
6 



90 

27.4 

12x14 

12 

14 

14X14 
10x14 
4x4 



44x14 

12 
16 
16 

12 

4x5 

16 

44 DW. 

54 to 12 

27 



. . in. i t 

Deck camber i in. per ft., Hdwd. hard wood, S.W. soft wood, (n) nominal, e.g. surfaced 



24x4 
24x12 

14 
6 

U 



the more expensive fully-shaped boat. Now, they are 
becoming aware of the merits of this method of con- 
struction which, experience has shown, can reasonably be 
expected to last from 20 to SO years. 

Table 22 refers to soft woods, such as firs and cedars. 
Yellow cedar is recommended because it has practically 
the same strength as West Coast firs but is slightly lighter 
in weight. The best grades of this are used for such 
members as the frames, floors, navels, filters, beams, 
keelsons and keel. Clears are used for the planking, 
vertical grain above water, slash grain below water. It is 



realized that vertical grain is difficult to obtain, but in 
warm countries it would greatly reduce maintenance 
costs. If hardwoods ,arc used, scantling sizes can be 
reduced considerably below those given, which are for 
soft wood. All flitch used must be dose-grained, select, 
structural, without sap, wane, rot or loose knots, all well 
bolted. A typical 57x16 ft. (17.4x4,9 in.) V-bottom 
boat is shown in fig. 127 and 128. The bays between the 
frames are filled in solid from keel to deck in the cargo 
hold. This provides insulation by the wood itself and 
makes a solid backing for the ceiling to resist the impact 



[139] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 




Fig. 126. 80 x 22 x 9 ft.(24.4x 6.7x2.7 m.) wood constricted ttma boat designed for service in South 4frlcan 
fisheries. Suitable for both seine and bait fishing. 300 h.p. 




Fig. 128. 57x16 ft. (17.4x4.9 m.) nvxxfc* K-/* combination boat 
Fig. 127. Midship section showing V-bottom construction of a vessel for Alaska seining and for crabbing. Suitable for 240 h.p. dlesel and 
of 57x16 ft. (17.4x4.9 m.) with two brine cooling tanks forward. Economical construction 




Fig. 129, Framimg wed In mailer sttel nueh from 45 to 73 ft. (13.7 to 223 m,) length, with 

/raiding oft and 



SCANTLINGS U.S. WEST COAST STEEL AND WOOD PRACTICES 



TABU 21 



LOA 



KM! . , . 
Stem (Hdwd.) 
Stern pott (Hdwd.) 

Keelson 
Sifter keelson 

Deadwoods . 
Shaft logs . 
Horn timber 

Gripe (Hdwd.) 
Frame spacing 
Frame taper . 
Flitch 

Beams, sided 
Beams, moulded . 
Beam spacing 

Bilge stringers 
Number of sttakes . 
Clamp, main deck 
Shelf, main deck . 
Ceiling, main deck . 

Clamp, raised deck 
Shelf, raised deck . 
Ceiling, raised deck 

Garboard 
Sheer strake . 
Planking 
Broad strake 

Guard (Hdwd.) . 

Sponson 

Shoe (Hdwd.) 

Decking 
Waterway . 

Rim timbers . 
Quickwork . 

Sag in keel . 





1 


UUMMIft 


priNMM. 


All&dgh 


soroftua 
mraqghai 


i*FMflKU 

dtobei ' 


NMKIOU9J 


EtpKllftJ 






ft. 


30 


45 


50 


57 


65 


75 


85 


100 


112 


125 


m. 


9.1 


13.7 


15.2 


17.4 


19.8 


22.9 


25.9 


30.5 


34.2 


38.1 


in. 


6x8 


8x8 


8x8 


10x10 


12x12 


12x12 


12x14 


14x14 


14x16 


16x16 


in. 


6 


8 


8 


10 


12 


12 


12 


14 


14 


16 


in. 


6 


8x12 


8x12 


10x16 


12x16 


14x18 


14 


16 


16 


18x18 


in. 


8x6 


6x8 


8x8 


10x10 


12x10 


14x12 


12X16 


14x16 


14x18 


16x18 


in. 


6x6 


6x6 


8x8 


8x10 


10x10 


12x12 


10x14 


12x14 


12x14 


16x1* 


in. 


8 


8 


8 


10 


12 


12 


12 


14 


14 


16 


in. 


8 


10x12 


10x12 


12x12 


14 


16 


16 


18 


20 


24 


in. 


8 


12 


12 


12 


14 


14 


16 


18 


20 


20 


in. 


8 


8 


8 


10 


12 


12 


12 


14 


14 


16 


in. 


12 


12 


12 


14 


16 


16 


18 


21 


22 


22 


in. 


6to3 


7 to 3 


7 to 31 


8to4 


8to4 


9to41 


10 to 5 


11 to 51 


12 to 6 


12 to 6 


in. 


2 


3 


3 


31 


4 


4 


41 


6 


6 


6 


in. 
in. 


3 to 6 
3 


4to8 
31 


4to8 
31 


41 to 91 


51 to 10 

4* 


51 to 12 


51 to 12 
5 


6 to 12 


6 to 12 


6 to 12 


in. 


18 


24 


24 


24 


27 


27 


27 


27 


30 


30 


in. 


2x6 


3x6 


3x6 


3x6 


4x6 


4x8 


4x8 


4x10 


6x10 


6x10 


. 


4 


5 


5 


6 


6 


7 


8 


8 


7 


8 


in. 


2x6 


3x8 


3x8 


3x10 


3x12 


4x12 


4x12 


4x14 


4x14 


6x14 


in. 


2x6 


3x8 


3x10 


3x12 


3x12 


3x12 


4x12 


4x10(2) 


4x10(2) 


6x10(2} 


in. 


l(n) 


If 


U 


2 


2 


2 


2 


3 


4 


4 


in. 


2x6 


3x8 


3x8 


3x12 


3x12 


3x12 


3x12 


4x12 


4x12 


4x12 


in. 


2x6 


3x6 


3x6 


2x12 


2x12 


3x12 


3x12 


4x12 


4x12 


4x12 


in. 


l(n) 


It 


1ft 


2 


2 


2 


2 


2 


2 


2 


in. 


U(n) 


2x10 


2x12 


2i 


21 


21 


3 


4x12 


5x12 


6x16 


in. 
in. 
in. 


l(n) 

ir 


2x10 

U(n) 
UxlO 


2x10 
U(n) 
UxlO 


2 
2 
21 


2 
2 
2t 


2 
2 

2t 


2J 

li 


21 

8 


3(n) 
3(n) 


3(n) 
3(n) 
4 


in. 
in. 


2x3 
None 


2x6 
2x8 


2x8 
3x8 


2 
4x91 


2 
4x12 


2 
4x12 


2 
5x12 


51x14 


5*xl4 


3 
6x14 


in. 


1* 


1ft 


2 


2 


2 


2 


21 


3 


3 


3 


in. 
in. 


Hx2 
Ijx6 


2x3 
2x12 


2x3 
2x12 


2x4 
2x12 


2x4 
2x12 


21x4 
2ixl2 


21x4 
21x12 


21x4 
2}xl2 


3x4 
3x14 


3x4 
3x14 


in. 


_. 


8 


10 


12 


12 


12 


12 


14 


14 


14 


in. 





4 


4 


6 


6 


6 


6 


6 


6 


8 



in. 



* 



1* 



li 



Deck camber J in. per ft., Hdwd. hard wood, (n) nominal e.g. surfaced 



of the free water, and does away with the possibility of 
loose water in the bilges. This is a typical fishing boat 
commonly called an Alaska limit combination boat, 
being designed for heavy liquid cargo in both holds: for 
carrying crabs, the water circulates and flows over the 
top of the hatch continuously. 



Scantlings for round- and V-bottom construction in sizes 
from small giQnetters up to larger boats, 130 ft. (39.6 m.) 
long, aw given in table 23. Compromises have been made 



with existing methods of construction by using both 
transverse and longitudinal framing for the same hull. 
Experience has shown this to be most practical and 
efficient, especially where light-weight plating is used 
Plate skegs with apertures are introduced for better 
handling, and so are heavy horn plates to eliminate strut* 
and reverse framing to a large extent These have all been 
proved and are recommended. 



Fig. 129 shows the framing used in smaller steel vessels,, 
from 45 to 75 ft (13.7 to 22.9 m.). Transverse framing it 



[141] 



FISHING BOATS OF THE WORLD; 2 CONSTRUCTION 




Fig. 130. Midship section of welded steel construction in a 65x18 ft. 
(19.3x5.5 m.) combination vessel 




Fig. 132. 83^22 ft. (25.3x6.7 m.) welded steel round-bottom 
combination vessel 




Fig. 133. 83 x 22 ft. (25.3 x 6.7 m.) welded steel round-bottom combination vessel 




1 



-tffxM-A CIMxM m. mcM* MM? V*oaom com- 

, 273 k*. OtMl, wftaMr 




fig. 134. 100x.Xxl3.7Sfl. (*Wx7.Px** .) 
comMnatUm frawt md ttaa fiiMi* tw 



SCANTLINGS U.S. WEST COAST STEEL AND WOOD PRACTICES 




Fig. J35. 100x26x 13.75 ft. (30.5 x 7.9 x 4.2 m.) all welded steel combination trawler and tuna fishing vessel 

with portable bolt tanks 



used aft of the engine room bulkhead, with longitudinal 
framing forward. Since the plating recommended for the 
45 ft. (13.7 m.) vessel is in. (4.75 mm.) thick, the 
framing is spaced more closely than the ordinary rules 
require. This is done to eliminate the washboard effect. 
To this end care must be taken not to over-weld plating 
to the frames. 

Fig. 130 and 131 show a 65x18 ft. (19.8x5.5 m.) 
welded steel V-bottom combination vessel with typical 
sections showing transverse framing aft of the engine 
room bulkhead with longitudinal framing forward. This 
type of construction is typical of all lengths of boat from 
45 to 75 ft. (13.7 to 22.9 m.). Since the arrangements, 
in the lengths under 35 ft. (10.7 m.) depart from standard 
and use lighter weight steel, complete longitudinal con- 
struction in these smaller sizes is recommended. 

Fig. 132 and 133 show an 83x22 ft. (25.3x6.7 m.) 
welded steel round-bottom combination vessel. This uses 
^ in. (7.9 mm,) plating, so transverse framing can be 
used without much trouble from washboard effects. The 
midship section shows framing built either transversely or 
longitudinally. Plate must be pressed over the entire hull 
surface, which is more costly than the V-bottom type. 
There is more space to work with here, therefore this 
added cost is not so important. 

Fig. 134 and 135 is a 100x26x13 ft. 9 in. (30.5x 
7.9x4.2 m.) all-welded steel combination fishing vessel 
with portable bait tanks for tuna fishing. With the tanks 
removed the vessel is used for seining and longlining. 
The steel weights comply closely with the ABS or Lloyds 
rules with the exception that the framing is more closely 
spaced for welding. The heavy shaded areas on the 
profiles of vessels indicate where heavy chafing plates are 
usually installed. The use of in. (1.6 mm.) heavier 
gunwale plate is recommended in all cases, thereby 



eliminating the extra cost of installing doubters in the 
trawl and seine lofts. 

Forward, where webs are used, intermediate floors 
between webs are recommended at the same spacing as 



All hull oftd haw ttM) work, whofwtr Mtura, dott n 

include to* haft, toil *aft or propdtoft 



90 
25 
20 



60 



20 



SO 



100 



190 



200 



250 feifOOO 



6 K>20304030070i090IOOIIOI*W 
t of tfwl 



Fig. 136. Steel weights in combination and tuna fishing vessels of 
lengths overall up to 114ft. (34.8 m.) 



the transverse framing, not only for increased strength 
but to help to eliminate vibrations in the hull. In some 
cases angled cants are used where there is a heavy flare. 

Where engine beds and shaft alley bulkheads are 
welded to the plating they act as vertical strength mem- 
bers, and regular vertical centre keelsons can be eli- 
minated. However, at the ends of the vessel they can be 
used to advantage. Aft, where the weld line rises to the 
stern with plate margin line, the heavy skcg plate should 
be brought forward inside the hull to form a vertical 
centre keelson in this area. 

Fig. 136 shows steel weight in relation to length. 



[143] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



TABLE 22 



LOA 



Keel . 
Stem (Hdwd.) 
Stern post (Hdwd.) 

Keelson 
Sister keelson 
Fkx>n (Hdwd.) 
Deadwoods . 
Shaft logs . 
Horn timber . 

Gripe . 
Frames 
Frame taper 
Frame spacing * 
Cants (S.W.) . 
Navel pieces at bilge 



.sided 
Beams, moulded 
Beam spacing 

Bilge stringers 
Number of strokes 
vj-iamp* mam oecic . 
Shelf, main deck . 
Ceiling, main deck . 
Chine (Hdwd.) 
Chine clamp 

Clamp, raised deck 
Shelf, raised deck . 
Ceiling, raised deck 

Garboerd . . 

Sheer strake . 
Planking 

Broad strake . 

Guard (Hdwd.) 
Sponson . 
Shoe (Hdwd.) 

Decking 
Waterway 

Rim timbers . . 
Quickwork . 

Sag m keel . 



Att siM ghreaiwttli a*i to be i 


ft. 


30 


45 


50 


57 


65 


75 


85 


90 


m. 


9.1 


13.7 


15.2 


17.4 


19.8 


22.9 


25.9 


27.4 


in. 


6x8 


8x8 


8x8 


10x10 


12x12 


12x12 


12x14 


12x14 


In. 


6 


8 


8 


10 


12 


12 


12 


12 


in. 


6 


8x12 


8x12 


10x16 


12x16 


14x18 


14 


14 


in. 


3x8 


4x10 


4x10 


6x12 


8x12 


8x12 


10x14 


10x14 


in. 


3x6 


4x8 


4x10 


6x12 


8x12 


8x12 


10x14 


10x14 


in. 


2x6 


3x8 


3x9 


3x10 


4x12 


4x12 


41x14 


41x14 


in. 


8 


8 


8 


10 


12 


12 


12 


12 


in. 


8 


10x12 


10x12 


12x12 


14 


16 


16 


16 


in. 


8 


12 


12 


12 


14 


14 


16 


16 


in. 


8 


8 


8 


10 


12 


12 


12 


12 


in. 


2 


3 


3 


3 


4 


4 


6 


6 


in. 


6to3 


7 to 3* 


8 to 3* 


8 to 4 


9 to 41 


9 to 41 


10 to 5 


11 to 54 


in. 


12 


12 


12 


12 


12 


12 


12 


12 


in. 


2Dbl. 


3Dbl. 


3Dbl. 


3DbI. 


4Dbl. 


4Dbl. 


4Dbl. 


4Dbl. 


in. 


2x8 


3x8 


3x10 


3x12 


4x12 


4x12 


4x14 


4x14 


in. 


3to6 


4to8 


4 to 8 


41 to 91 


51 to 10 


51 to 12 


51 to 12 


51 to 12 


in. 


3 


31 


3* 


4 


4t 


41 


5 





in. 


18 


24 


24 


24 


27 


27 


27 


27 


in. 


2x6 


3x6 


3x6 


3x6 


4x6 


4x8 


4x8 


4x8 


m 


4 


5 


5 


6 


6 


7 


8 


8 


in. 


2x6 


3x8 


3x8 


3x10 


3x12 


4x12 


4x12 


4x12 


in. 


2x6 


3x8 


3x10 


3x12 


3x12 


3x12 


4x12 


4x12 


to. 


l(n) 


H 


1} 


2 


2 


2 


2 


2 


in. 


3x6 


3x8 


31x8 


4x8 


5x91 


6x10 


6x10 


6x10 


in. 


2x8 


3x10 


3x10 


3x10 


3x12 


4x12 


6x12 


6x12 


in. 


2x6 


3x8 


3x8 


3x12 


3x12 


3x12 


3x12 


3x12 


in. 


2x6 


3x6 


3x6 


2x12 


2x12 


2x12 


3x12 


3x12 


in. 


l(n) 


1* 


11 


2 


2 


2 


2 


2 


in. 


li(n) 


2x10 


2x12 


21 


21 


21 


3 


3 


in. 


l(n) 


2x10 


2x10 


2 


2 


2 


2J 


2t 


in. 


Kn) 


H(n) 


H(n) 


2 


2 


2 


2i 


2* 


in. 


U 


lixlO 


11x10 


2i 


2t 


2t 


21 


21 


in. 


2x3 


2x6 


2x8 


2 


2 


2 


2 


2 


in. 


None 


2x8 


3x8 * 


4x91 


4x12 


4x12 


5x12 


5x12 


in. 


U 


U 


2 


2 


2 


2 


21 


21 


in. 


Ux2 


2x3 


2x3 


2x4 


2x4 


2ix4 


21x4 


21x4 


in. 


Hx6 


2x12 


2x12 


2x12 


2x12 


21x12 


21x12 


21x12 


in. 


rr . 


8 


to 


12 


12 


12 


12 


14 


in. 





4 


4 


6 


6 


6 


6 


6 



. in. i I t 1 1* U II 

Deck camber i in. per ft, Hdwd. - hard wood, S.W. - soft wood, (ft) - nominal, e.g. surfaced 



[144) 



SCANTLINGS U.S. WEST COAST STEEL AND WOOD PRACTICES 



TABLE 23 



LOA 


ft. 


30 


45 


50 


OT 

57 


65 


75 


85 


v n. t.i IP jv, 

100 


*m.) 
112 


130 




m. 


9.1 


13.7 


15.2 


17.4 


19.8 


22.9 


25.9 


30.5 


34.2 


39.6 


Stem bar . 


in. 


ix6to3 


fx6 


tx6 


1x6 


1x6 


Iix6 


I|x6 


I}x6 


11x6 


Hx6 


Keel 


in. 


ix6 


|x6 


1x6 


Iix6 


Iix6 


1}X6 


Ifx6 


Ifx6 


I}x6 


1JX6 


Stern post. 


in. 


i 


i 


i 


i 


i 


i 


li 


Iix6 


1^x8 


Hx8 


Skeg . 


in. 


i 


t 


i 


i 


i 


i 


i 


1 


li 


li 


Horn plate 


in. 


i 


t 


i 


i 


i 


4 


1 


li 


li 


li 


Gudgeon plate . 


in. 


ix3 


Iix6 


Ijx6 


1Jx6 


Ijx6 


I}x6 


Iix8 


2}x8 


3x9 


5x10 


Rudder . 


in. 


1 


i 


i 


i 


* 


i 


t 


i 


I (streamlined side plates) 


Rolled stem plate 


in. 


i 


i 


i 


i 


t 


* 


ft 


* 


i 


i 


Rolled stern plate 


in. 


i 


ft 


i 


i 


i 


I 


i 


A 


A 


A 


Stern stiffeners . 


in. 


Ifxljxi 


2ixlixi 


3x2xJ 


3x2xi 


3x2xi 


*IA V ?A V X 

Jj| A X| A f 


3ix2ix 


i 4x3ixA 


4x3*x-d 


^ 5x3ix* 


Centre keelson 


in. 


None 


ft 


ft 


i 


i 


J 


i 


A 


* 


A 


Engine bed, vert. 


in. 


i 


i 


1 


i 


i 


A 


A 


A 


i 


i 


Engine bed, top 


in. 


i 


i 


i 


i 


i 


l 


1 


li 


u 


u 


Shaft alley, vert. 


in. 


None 


i 


i 


i 


* 


i 


* 


A 


* 


* 


Frames, transverse 


in. 


None 


2ixlixi 


3x2xi 


3x2xi 


3x2xi 


3ix2ixi 


3ix2ix 


i 4x3xA 


4x3x* 


5x3ix 


Trans, frame 
























spacing . 


in. 


None 


15 


15 


15 


18 


20 


21 


22 


23 


24 


Web frame* . 
Web frame spacing 


in. 
in. 


*x3 
30 


5x2xiT 
45 


6x3xiT 

45 


6x3xiT 

45 


6x3xiT 

54 


7x3xAT 
60 


1 Transversely framed 


/None 
INone 


Framesjongitudinal in. 


Uxlixft 


2ixlixft 


3x2xi 


3x2xi 


3x2xi 


3ix2ixi side stringers 10 xi (2 required) 


None 


Long, frame spacing in. 


12 


15-18 


18 


18 


18 


18 








None 


Floors, plate . 


in. 


ft 


i 


i 


i 


i 


i 


i 


A 


A 


ft 


Floors, flange . 


in. 


2 


li 


2 


2 


2 


2i 


2i 


3 


3 


3i 


Floors spacing . 


in. 


15 


15 


15 


15 


18 


18 


21 


22 


23 


24 


Bulkheads, lower pi 


in. 


i 


A 


i 


i 


i 


i 


i 


j 


A 


A 


Bulkheads, upper pi 


.in. 


i 


ft 


A 


A 


A 


A 


i 


i 


t 


i 


Bulkhead stiffeners 


in. 


Uxlixft 


2ixlixi 


3x2xi 


3x2xj 


3x2xi 


"\i v 54 v 4- 

? j A +f A J 


3ix2ix 


1 4x3xi 


4x3xJ 


4x3xi 


Beams t 


in. 


Uxlixft 


2ixlixi 


3x2xi 


3x2xi 


3x2xi 


3ix2ixl 


3ix2ix 


i 4x3xi 


4x3xJ 


5x3*x* 


Beam spacing . 


in. 


15 


15 


15 


15 


18 


21 


21 


22 


23 


24 


Deck plating . 


in. 


i 


ft 


A 


A 


i 


j 


i 


i 


^ 


A 


Shell plating . 


in. 


i 


ft 


A 


i 


i 


i 


i to A 


A 


A 


ft 


Bilge plate 


in. 


i 


i 


i 


i 


1 


1 


None 


None 


None 


None 



Plates and shapes to have a minimum tensile strength of 58,000 to 68,000 p.s.i. 



(145] 



STRUCTURAL TESTING OF SMALL CRAFT 

by 
YOSHINORI OTSU, NOBUTATSU YOKOYAMA and TSUTOMU KOBAYASHI 

Traditional Japanese coastal fishing boats are simple and inexpensive to construct. The hull has wide wood planking and its nail* 
jointed seams am much sttonfor than expected. The longitudinal members have a large safety factor. Transverse deformation may be caused 
unless the hull is fixed by beams suitably spaced. 

L'ESSAI DE PETTTS BATEAUX EN VRAIE GRANDEUR 



Les bateaux -be 
de bord6 et ses cootures 



cdtiers trmditionnels japonais sont de construction simple et peu coftteuse. La coque a de Urges tements 
sont beaucoup plus fortes qu'on ne la pcnsait. Les membrures longitudinalcs ont un grand factcur de sccuritc. 



H pent y avoir tme deformation traitsvemle, a moins que la coque soit fixee par des barrots convenablement espaces. 



ENSAYOS DE BARCOS PEQUENOS A TODA ESCALA 

Las embaicaciones tradicionates japonesas dedicadas a la pesca costera son sencillas y baratas de construir. El casco es de pianchas 
de madera de mucha anchura y la davmzon resuha mucho mas fuertc de lo que se podria suponer. Los mtembrot longitudinalcs ticncn un 
gran factor de seguridad. Puede ocasionarsc una deformaci6n transversal a menos que el casco se asegure mediante baos bien espaciados. 



THERE are more than 130,000 small unique fishing 
craft from 1 to 5 GT along the open and sheltered 
coasts of Japan, most of them are operated as 
small individual enterprises. The boats are built up of 
wide wooden planks without a complete frame system 
as shown in fig. 137 and 138, called the Yamato type. 

The example in fig. 137 has the following principal 
dimensions.* 

LBP-21.5 ft. (6.55 m.) 
B = 4.43 ft. (1.35 m.) 
D = 1.80ft. (0.55m.) 
GT = 0.95 

They are said to have been developed from a primitive 
15th century dug-out vessel. The Yamato boats are used 
for net fishing, pole fishing, lining, shore seining, etc. 
They are now mostly mechanised with small kerosene, 
semi-diesel or diesel engines but the sail and the rowing 
scull peculiar to the region are still used, although more 
as auxiliary power during fishing than for emergency 
propulsion. 

The building cost of the Yamato boat is about half 
that of the round-bottom type. It is easy and economical 
to maintain and has a good performance when riding on 
the turf and beaching. The weak point is the tn 



strength, because of the incomplete framing. The length 
is thus limited to about 50 it (15 m.). Larger boats with 
frames are constructed and are called improved Yamato 
or the compromise Japanese type. 



Constructional knowledge and experience have been 
passed on from individual boatbuildcrs to their appren- 
tices, without any drawings or calculations so, naturally, 
there are many variations in the details of the hull form. 
Nevertheless, there is a fair amount of standardization, 
and the common constructional features can be sum- 
marized. 

GENERAL DESCRIPTION 

The hull is made of five fiat or slightly bent wide wooden 
planks and a transom, as illustrated in fig. 139. The 
planks are cut to complete developed shapes and nailed 
up while being pressed into place by props or stays. 
The bottom and side planks are often neither caulked nor 
filled with a sealing compound; they are merely nailed 
after the joints are fitted by sawing, when they are in 
position. 



The sides and the bottom planks are transversely rein- 
forced with wooden knee-brackets of naturally shaped 
timber, usually spaced about 3.3 or 6.6 ft. (1 or 2 m.) 
apart Floor timbers ait placed from chine to chine at 
the brackets, or sometimes in between. The floor 
timbers ate nailed or bolted to the hull planks. The 
transom is a thick plank fitted a little forward from the 
stern to form a recess for the rudder and the lifted 
propeller. Mechanized boats are strengthened by bulk- 
heads for and aft of the engine. 



'(Mi! 



SCANTUNOS STRUCTURAL TESTING OF SMALL CRAFT 




tfcii """" ^* 



Fig. 137. Construction plan of Yamato type, built of wide wooden planks, without a complete 

frame system 



Longftudiiiftl strength 

This is obtained from the hull planking only, except for 
the guard and rail. There is no deadwood, keelson and 
bilge strake s found in normal round-bottom boats. 

Usually there is a rowing thwart and a steering place 
aft, an engine trunk just forward, and an open space for 
fishing operations between the engine bulkhead and the 
short bow deck, with a wave breaker. The boats often 
have beams passing through both sides to hold additional 
rowlocks and/or to lay masts and long poles. 

Fittings and equipment 

Two or three masts for single square sails with yards are 
used when the boats are fishing, as shown in fig. 140, 
and sometimes for sailing. The rowing sculls are operated 
at the stern or the side in a unique manner. Usually a 



man stands on the stern thwart and with a single scull 
placed on a pivot on the transom, stirs the water behind 
the boat with a regular, rocking motion of pulling and 
pushing athwart the handle of the oar. The scull blade 
has an ogival section to produce a propelling action, as 
shown in fig. 141. 

Dimensions 

Some representative boats are listed in table 24. The 
most popular size is between 1 5 and 40 ft. (4.6 and 1 2.2 m.) 
in length, with a beam of 3.6 to 8.5 ft. (1.1 to 2.6 m.). 
The L/B ratio ranges from 4 to S. Yamato boats are 
normally under 50 ft. (15.24 m.). Boats from 40 to 60 ft. 
(12.2 to 18.3 m.) are normally a combination of the 
traditional and modern type. Larger boats are usually of 
round-bottom design. 




Fif. 138. Ltar of the Yamato type 
[147] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



floor timber 
frome 



pivot f < 




side plonk 

wing plonk 
keel plonk 
rubbing shoe 



rudder socket 

tronsom 
recess for lifted propeier 

Fig. 139. The Yamato boat, which Is made of five flat or slightly 
bent planks 



Power 

The majority have recently been converted into power 
boats, using small kerosene engines with electric ignition, 
semi-diesels, or small diescls from 1 to SO h.p. The speed 
range is from 6 to 7 knots. These engines are easily 
maintained, spare parts and skilled labour being readily 
available in any village. As the propeller shaft is made to 
be lifted when landing or rowing in shallow water, a 
square slotted timber is fixed aft above the keel to provide 
a recess for the lifted shaft. A description of the system 
is given on p. 29S. 

STRUCTURE TEST 

The methods for calculating the longitudinal strength of 
steel ships are so far as is known never used on wooden 
ships, and to ascertain if steel ship calculations are suitable 
for wooden boats, a preliminary test of the structural 
deflection was made with an improved Yamato boat, the 
Akatsuki of the Fishing Boat Laboratory of the Japanese 





Fig. 140. Singh to* 



Fisheries Agency. This boat has the typical wide plank- 
ing but a frame system, as shown in fig. 142. 

The boat was placed on two keel blocks, 24 ft (7 .3 m.) 
apart, and loaded amidship with weights from 980 to 
4,750 lb. (445 to 2,159 kg.). The deflection was measured 
by piano wire stretched between the bow and the stern. 
Dial gauges were placed under the keel and optical 
measurement made by mirror, telescope and catheto- 
mcter. The results were: 

(1) There is a linear relation between load and 
deflection in a wooden ship, even in such severe condi- 
tions that the maximum shearing force is 4.16 times the 
calculated sagging force for the 1/15 wave, the greatest 
bending moment being 4.33 times that estimated for the 
same wave. 



push or pul othwortehlpt 
pivot 




fa art fitted on two or three motto in the 
Yamato boat 



relative flow 
hydrodynomfc lift 

propelling component 



Fig. 141 . Rowing scull Having an ogival section to produce a propelling 

action 



(2) Modulus of elasticity can, therefore, be assumed 
and the usual method for beam calculations applied. 
This test indicated the equivalent Young's modulus of 
elasticity E- 197,000 Ib./sq. in. (13,850 kg./sq. cm.). One 
of the test results is shown in fig. 143, where the computed 
deflection, assuming =2,276,000 Ib./sq. in. (160,000 kg./ 
sq. cm.), is represented by broken lines. 

(3) When the load was removed there was not com- 
plete recovery. The reason was not dear but it might 
have been permanent strains or slip in the timber and the 
nails, 

(4) The transverse deformation at the open hold was 
for greater than expected, as shown in fig. 144. Trans- 
verve members, such as beams, floor timbers and bulk- 
heads, should be carefully arranged during construction. 

(5) Hie longitudinal deflection was only 0,4 in. 
(10 mm.) even though the applied stress was severer 



[148] 



SCANTLINGS STRUCTURAL TESTING OF SMALL CRAFT 



"AKATffJKI" 

LBP.36lft(H.Ofn) 
B 72 W22m) 
D - 295ft(09rrO 



1 Coornmg 

2 Cowing bort,* 
3 Deck plonking 

4 Girder 

7 5 Fenow 

6 Shelf 

7 Stroke A 

8 Stroke B 

9 Bilge stringer 

10 Strokes C,D 

11 Stroke E 

12 Short block 

13 Keel 
* Shoe 

" -/ 




Fig. 142. General arrangement of an improved Yamato type, the Akatsuki, with typical wide planking 



. nptfimtritfl 

2276000 
(160000 




Fig. 143, Longitudinal deflection of AkaUuki 



[149] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 





i 


kjr -*- MMrf 


TABU 

Itn 1 ft M! 11 1 


24 






WMH fMl 

Type of boa* 


LtngthiL) 


**< 


Ap*(H> 


Engine (k.p). 


Pok KM fiahtag (skip-jack) . 


. 


it 
m. 


50 
15.24 


9 
2.74 


4.0 to 4.5 
1.22 to 1.37 


s. 30 to 50 


Saitingtrawte . 





ft 
m. 


45 
13.72 


8.5 
2.59 


3.5 
1.07 


k.d. 8 to 10 


Net fishing (sardine) 


. 


ft. 
m. 


40 
12.19 


5to9 
1.52 to 2.74 


4.5 to 5 
1.37 to 1.52 


s. 25 to 30 






ft. 


35 to 36 


6.2 to 7.0 


2.4 to 2.5 


k. 6.5 to 8 






m. 


10.67 to 10.97 


1.89 to 2.13 


0.73 to 0.76 


d. 15 


Sailing trawler (shrimp) 


. 


ft. 
m. 


27 to 36 
8.23 to 10.98 


7to9 
2.13 to 2.74 


3.0 to 3.5 
0.91 to 1.07 


k. 8 
d. 6 to 10 














s. 10 to 15 


Pole flhfog (miscellaneous) 


. . 


ft 


23 to 25 


5.2 to 5.3 


1.7 








m. 


7.01 to 7.62 


1.58 to 1.62 


0.52 




Pole fishing (miscellaneous) 


. 


ft 
m. 


18.0 to 22.5 
5.49 to 6.86 


4.5 to 5.5 
1.37 to 1.68 


2.0 to 2.5 
0.61 to 0.76 


k. 5 to 6 


Abbreviations: k. kerosene engine 


d. diesel engine 


s. semi-diesel engine 








**+ 


TABLE 


25 






Number 




Sates 


sin various eon 
Bending 


Number 




Shearing 


in Member 


Material 




stress 


in Member 


Material 


stress 


fig. 142 






lb*/SQ.in* 


fi*. 142 




lb./sq.in. 






( 


li/sqxan.) 






(kg./sq.cm.) 


2 Covering board . 


. Zelkova 




217 


1 Coaming 


. Zelkova 


37.1 








(15.27) 






(2.61) 


5 Fender 


. Cypress 




197 
(13.81) 


2 Covering board 


. Zelkova 


5.5 

(0.39) 


6 Shelf . 


. Zelkova 




189 


3 Deck 


. Cedar 


3.3 

/A *)1\ 








(13.28) 


4 Girder 


. Zelkova 


(0.23) 
21.6 


7 StrakeA . 


. Cedar 




203 






(1.52) 








(14.29) 


5 Fender 


. Cypress 


21.6 


8 StrakeB 


. Cedar 




83 
(5.83) 


6 Shelf 


. Zelkova 


(1.52) 
21.6 


Girder A . . 


. Cedar 




62 


7 StrakeA . 


. Cedar 


(1.52) 
41.0 








(4.29) 






(2.87) 


Girder B . 


. Cedar 




46 


8 StrakeB 


. Cedar 


44.9 








(3.20) 






(3.16) 


9 Bilge stringer 


. Cypress 




35 


9 Bilge stringer 


. Cypress 


21.3 








(2.47) 






(1.49) 


10 StrakeC . 


. Cedar 




70 


10 StrakeC . 


. Cedar 


5.1 








(2J4) 


10 StrakeD . 


. Cedar 


(<U6) 


10 StrakcD . 


. Cedar 




72 






(0.81) 








(5.05) 


11 StrakeE . 


. Cedar 


22.6 


11 StrakeE . 


. Cedar 




110 

(7.71) 


12 Shaft Wock . 


. Zelkova 


(138) 
37.0 


13 Ked . 


. Zelkova, Cypress 


126 


13 Ked . 


(2.60) 
. Zelkova, Cypress 21.6 








\9*B I/ 






(1.52) 


14 Keel shoe . 


. Cypress 




142 


14 Keel shoe 


Cyprass 


l s!r 








(9.95) 






(0.57) 



[150] 



SCANTLINGS STRUCTURAL TESTING OF SMALL CRAFT 

than would occur at sea. This seems to be due to the 
wide side planks and the nails along the chine. 

(6) The calculated stress on each member in the 
severest test is shown in table 25. 

The safety factors were 35 for compression, 88 for 
tension and 16.5 for shear. These results suggest that 
the structure of the Yamato type is much stronger than 
previously estimated and the scantlings might possibly 
be decreased to save hull weight However, there must 
always be a margin for deterioration and easy repair. 

The longitudinal strength of the type was proved to 
be more than sufficient, but transverse strength should 
be increased, preferably by means of beams or thwarts 
closer spaced than 6 ft. (2 m.). The easy construction 




US] 



Fig. 144. Transverse deformation o/Akstsuki 



will save much labour and material, but skill is needed 
for caulking, nailing, planking, etc. 



[151] 



STANDARD SCANTLINGS 

by 
DWIGHT S. SIMPSON 

The scantlings of 22 successful fishing vessels from 50 to 150 ft (15 to 43 mj were investigated. As length, beam and depth are 
known at the beginning of construction, and final displacement and gross tonnage are more difficult to estimate, the unit load was formulated : 
N-^CLOAxBxD/lOOinfeet, and N^(LOAxBxD/2.83) in the metric system. Due to the small variation in block and prismatic 
coefficient!, it was considered that any difference in scantlings due to the sharpness of the vessel could be neglected. It was also assumed that 
the sectkm modulus of the fhunes will vary as the unit load and as the square of the frame length. The frame length is related to F [(B4-D)/2]" 
in feet, or F-Z69 (B4-D) 1 in the metric system. 

Diagrams are given from which the frame sections and frame spacings can be determined from the numerals. A table recommends 
the plank thickness in fetation to unit load and frame spacing. Similar diagrams are given for the determination of deck beams. The 
tHmffliBjf for keel, stem, keelsons, garboard strakes and other longitudinal members are determined in relation to the plank thickness. 

A wooden ship is no better than its fastenings, and an over-fastened one is equally bad. A hole is still just a hole and subtracts from the 
strength of the timber. Common fastenings are discussed and formulas given for permissible loads in various types of timbers. Correct 
roe-boring is important Round fastenings give better holding power than square ones, weighing 33 per cent. more. On a weight basis small 
f^fiijny have greater holding power than large ones, and they are less liable to split the wood. Hot dip galvanizing gives ferrous fastenings 
amazing life. Timber connectors might increase the holding power in sheer of a fastening about five times. Recommendations are given. 
expressing the diameter of the fastening as a fraction of the member h is to connect. 

SUGGESTIONS POUR DBS ECHANTILLONS STANDARDISES 

On a fait des recherches sur les echantillons de 22 navires de peche mesurant de 50 a 1 50 pi. ( 1 5 a 43 m.) et donnant toute satisfaction. 
Comme la longueur (Lht), la largeur (B) et le crcux (D) sont connus au d6but de la construction et que k emplacement final et la jauge brute 
sont d'unc estimation plus difficue, on a etabli la formule suivante donnant la charge spedfique: N~f (Lht xBxD/100) dans le systeme 
d'unite* anglnttrs, et N- V (Lht x B x D/2,83) dans le systeme metrique. A cause de la faibie variation des coefficients paralleltpipedique et 
prismatique, on a consider* qu'il eiait possible de negliger toute difference dans les echantillons due a la finesse du navire. On a aussi admis 
que le module de flexion des membrures varic comme la charge specifique et comroe k carre de la longueur de la membrure. La longueur de la 
membrure est en relation avec F((B+D)/2P dans k systeme <f unites anglatses ou F 2,69 (B+D) dans le systeme metrique. 

est donae des diagrammes a partir desquels on peut determiner les sections des membrures et leur espacement d'apres N x F. Une 
table recommande repaisseur du bord6 en relation avec la charge specifique et respacement des membrures. Des diagrammes similaires 
fervent 4 la determination des barrots de pont. Les echantillons pour la qullk, 1'etrave, les carlingues, les virures de gabord, et autres pieces 

WngfM^^W m^t Afct^rmm^t r+l.ti AI^P 1'epaiSSeUr du horde. 

Un navire de bois vaut ce que vatent les assemblages de ses differentes parties, et un exces de liaisons est egakmem mauvats. Un 
trou n'est qu*un trou et retire de la resistance a la piece de bois. Les assemblages courants sont examines, et 1'auteur donne des formulas pour 
les charpes pouvant etre autorisees pour divers types de pieces de bois. Le forage des avant-trous est important. Les pieces d'assemblage 
rondes (clous, boutora, etc.) remplissent mieux leur fonction que ks pieces carrees, qui pesent 33% de plus. Sur la base du poids. de petite* 
pieces d assemblage ont tine meiUeure action de liaison que de grandes pieces et sont moins susceptibles de faire eclater le bois. La galvanisation 
par trempage a chaud assure aux Ifaisonf de fer une duree etonnante. Les rondelks monies de dents peuvent augmenter de cinq fois environ la 
resistance au dsaiDement d*un assemblage. L'autcur donne des recommandations exprimant le diametre des pieces d' assemblage comme une 
fraction de felement a lier. 

SUGESTTONES PARA ESCANTILLONES NOR MALIZ ADOS 

Se investigaron los escantillones de 22 barcos de pesca que median de SO a 150 pies (15 a 23 m.) y que habian dado resultados muy 
satisfactorios. Como la eslora (LOA). la manga (B) y el puntaf(D), se conocen al conuenzo de la construcci6n y como el desplazamiento 
final y el tooelaje bruto son mas diflate* de cafcular, seestableci6 la siguiente fdrmula que da la cam especffica: N=^ (LOAxBxD/100) 
en el sittcro* de medidas briUnicas y N- </ (LOA x B x D/2,83) en el ststema m6trico. DeWdo a Jo pcquefta* que son las variadones de 
los ooeAdemes de Moque y prismatico, se crey6 ouc se podria hacer caso omiso de cualquier difierenda en los escantillones debida a la finura 
<telbarco. Tambien se supuso que el m6dulo de flexi6n de las cuadenias variaria como u caiga espedfica y cotro 
de lacuadenML La longtaid de la cuaderna esta en reladdn con F-[(B-HD)/2] en el staema de medidas britanicai o F-2,69 (BH-D)* en 
el sMrtwna metrico. 

SedandiagcamascoalMOttalessepiiedeadetenniiia^ Una tabla recomienda 

1 eepescr de la pianchas con idadte a la ourga emdftea y d es^ 

de los baot de la cubierta. Lot escantillones para la quilla, (xmtr^uilU, Ublones de apankiun y otnu piezas longitudinal 
con reladdn al ospesor de las plandias. 



El valor del barco de madera lo da la davaz6n; una clavazdn excesiva es perjudicial. Un agitfero no es nada mas que 
im agi^o y hace pettier resistenda al trozo de madera. Se examinun las clavagooes corrieiites y se dan fttrmulas para las carpas autorizadas 
para divenas dates de madera. El barreoado exacto es muy importante. El material de davaz6n (clavos, pernos, etc.) redondo es major 
<iue d cuadrado, qucpcsa 33% mas. Bassndose en el peso, las clavaiooes pequeflat sujatan mejer que las grandes y la roadera esta meoot 
xpuesta a agrietarse. La gsivsitoddp eo calicot da a la davaa6n dc hkrro una extr aordinaria duraci6n. Las annddas dentadas pueden 
aumentar hasta cinco veoes la resistencia de la davaz6n. Se hacon ncomendadones en Us que se expresa d diametro de la davaz6n como 
una f racctdn dd miembro que tienc que conectar. 



SCANTLINGS SUGGESTED STANDARD? 



Y TT THATreasonsarethereforesUblishingminimum 
m/m/ standards of construction? Who benefits? The 
f T answer is: all concerned with fishing boats. 
The owner can rest assured that his vessel is soundly 
built in accordance with the best experience, and able to 
withstand the hazards of her trade for a reasonable 
number of years with no undue maintenance costs. 

The builder knows that he and his rivals are bidding on 
approximately the same construction, a sort of "fair 
practice* 9 arrangement that should put him on his mettle 
to improve his workmanship as well as to watch his 
management and his buying methods. 



merely the individual detigner's or builder's customary 
practice. They vary in length from 50 to 140 ft (15 to 
43 m.) and in proportions as in table 26, 

The lowest freeboard in ready*for-sea condition varies 
from .32D to .45D. The higher percentage generally 
pertains to the smaller vessels, although the newer large 
vessels are approaching .4D. These relationships are 
shown graphically in fig. 145. 

With few exceptions, keels, frames, stems, sternposts, 
planking and beams are of oak. Keelsons and other 
longitudinal members are generally of fir, with some of 
oak, and decks and bulkhead sheathing of pine or fir. 



600 



FISHING BOAT 
PROPORTIONS 



50 60 70 60 90 100 IK) 120 190 140 fl 




J 



20 



30 
Length overall 



40 



Fig. 145. Relationship between displacement, length overall, beam and depth of U.S. East coast 

fishing boats 



The insurance companies would have more confidence 
in rule-built vessels and, if properly powered and equipped, 
such vessels should enjoy lower insurance premiums. 

These ideas were brought out at a 1954 meeting of the 
Western Hemisphere Committee appointed by the 1953 
FAO International Fishing Boat Congress in Miami. The 
Committee found there were so many variations in 
methods and countries that it decided to "start from 
scratch" with an investigation of a number of satisfactory 
fishing boats in service. 

The icMitHfy of 22 fishing vessels, built in New 
England and Nova Scotia, which vary in age from 5 to 
18 years and have stood up to year-around fishing from 
Georges to the Grand Banks, about as hard service as 
fishing vessels find, were selected as a base. 

Hie designs of these "specimen" vessels represent the 
Work of six well-known naval architects and builder- 
designers. Three of them arc classed with the American 
Bureau of Shipping, three were approved by the Canadian 
Steamship Inspection Service, and the rest represent 



All have ice sheathing along the forward two-thirds of 
the waterlinc and extended to the rail in way of the trawl 
gallows, usually 1 in. (2.5 on.) thick of oak, but some- 
times of greenheart. For typical midship section, 
arrangement of fastenings and nomenclature, see fig. 146. 
The original analysis of this data followed closely the 
method used by Smith (1950) for smaller craft based on 
displacement. Spots were widely scattered on all methods 
of plotting. It was found that the displacement figures 
were not reliable. Many lines drawings were not avail- 
able, and accurate flotation lines were almost impossible 
to get. Displacement figures given by designers or 



TABLE 26 



LOA/Bfrom3,12to 3.26 with an avenge of 4.23 

LOA/D 6.75 11.06 , S.33 

3/D 1.76 2J8 1.93 



[153] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 




Fig. 146. Typical midship section of wooden trawler showing fastenings and nomenclature 



builders differed from light to loaded and are not 
comparable. The use of under deck tonnage would be a 
sound base, but the tonnage is not likely to be known 
until the vessel is approaching completion; therefore it 
seems as difficult for the builder to use as displacement 
Some other criterion had to be found 

HULL UMBERS 



To quote Smith: "The values for frame spacing and hull 
plank thickness have been developed on the assumption 
that the primary (structural) function of the planking is 
to present a certain degree of resistance to lateral deflec- 
tion and if sufficient to provide this stiffness, it will be 
more than ample to sustain its function as a principal 
member of the longitudinal hull girder." To which may 
be added the fUrther assumption that, since this analysis 
is based on satisfactory existing vessels, frames and 
planking should be of sufficient size to withstand all the 
hazards of the service. 

It has been suggested that frame moulding should be 
sufficient so that planking and ceiling, considered 
together, constitute a trusstike structure. Perhaps usage 
and survival have already developed this system. The 
combination of planking, bilge ceiling and frame 
moulding produced herein have a high stiffness factor. 

Length, beam and depth are known at the beginning 
construction. A cubic number based on LOAxBxD 
seems to be as good if not a bettor indication of vessel 
size than displacement, and has been used in this analysis. 

It is recognized that a wide variation in (he Mode or 
prismatic coefficients would require a modification of the 



scantlings, but fishing vessels in the size under investiga- 
tion vary only from .420 to .500 in block and from .575 
to .645 in prismatic. Within these limits scantling 
differences can be neglected. 
Smith again proposed that "the section modulus of the 



TABLE 27 



Comparteon of 



Line Item 


Vessel No. 6 


Vessel No. 12 


Vessel No. 20 




ft. m. 


ft. m. 


ft. m. 


1 LOA 


. 68.0 20.75 


85.0 25.9 


115.86 35.3 


2 B 


17.0 5.18 


19.58 5.96 


23.75 7.25 


3D. 


8.83 2.69 


9.58 2.92 


14.25 4.35 


4 A. ready for sea 
5 LOA/B . 


78.5 
4.0 


125.0 
4.35 


367.0* 

4.87 


6 LOA/D . 


7.7 


8.86 


8.14 


7 B/D 


1.93 


2.10 


1.66 


89. 


0.589 


0.636 


0.628 


9 #A, 
10 N . 


4.27 
4.68 


5.00 
5.51 


7.17 
7.26 


11 Line 9/Line 10 


0.910 


0.908 


0.985 


12 tG . 


14.8 4*52 


ft. m. 
17.33 5.3 


//. m. 
215 6.86. 






jfoo' 38.7*' 


so. ft. so. m 
508.0 47.2 


14 B* 


289.6 26J 


3834 35'.5 


562.0 52.2 


15 F ! ! 


167.0 


212.5 


363.0 


16 Line 13/Une 14 


0.764 


0.785 


0.905 


17 Line 13/Line 15 


1.32 


1.41 


1.41 



Note: It will be 
i vinaoott 
in Hot 17 it 



in line 16 



4.3 and 
Jit of vtiicto, (B+DV2 hu tan wed 
thehAlf-^thfigum. SimiUrty,linell 
between ISei 9 tad 10. 



1154] 



SCANTLINGS SUGGESTED STANDARDS 



frame, Z per unit length of vessel will vary as the unit 
load and as the square of the frame length. The unit load 
can be shown to vary about as the cube root of the 
displacement" [for which the writer has substituted the 
more readily obtainable N^(LOAxBxD/100) feet 
or -^(LOAxBxD/2.83) metres]. 

Smith assumed that in smaller vessels the proportion 
of beam to depth remains about constant and substitutes 
B 1 for the square of the frame length. This would appear 
to put a double penalty on beam, possibly leading to 
narrow fishing vessels; therefore in this proposal, frame 
length has been related to F^KB+D)/!] 1 feet, or 
F=2.69 (B-fD) 1 metric. Table 27 gives some data of 
vessels selected from 22 base vessels which seems to 
justify this assumption. 

Thus, the section modulus of the frame, Z, has been 
determined to be Z=0.15xNxF. This is shown 
graphically in fig. 147. 

The frame, Z, is measured at the turn of the bilge and 
is considered for only one futtock of the double frame. 
The proportion of frame siding to moulding used is the 
average of the "specimens" and is very close theoretically 
to the section most economical in material. 

Fig. 148 gives nomograms with which one can deter- 
mine the frame dimension and frame spacing in feet and 
metres respectively from the section modulus per foot of 
ship's length (Z). Further, fig. 149 gives the moulding at 
deck and keel for a given moulding at bilge and the same 
siding. 

Bent frames 

Too few vessels over 50 ft. (15.25 m.) with bent frames 
were investigated to warrant definite conclusions. The 
indications are that Z for a complete bent frame may be 
about the same as Z for a single futtock of the sawed 
frame. Plank thickness may also be about the same as for 
sawn frame construction, but frame spacing must be 
closer so as to leave about the same space between frames 
as resulted by standard sawn frames. Up to 3 or 3} in. 



cuia 
45 

40 



X 

Z 
<0 

6 
H 







30 



2O 

15 
10 



800 1600 2400 3200 

N*F 

Fig. 147. Section modutii of frames 



(76 or 89 mm.) thick frames may be bent in a single stick 
and should be sided and moulded the same. If a greater Z 
is required, the frame should be in two or more parts 
laid on top of each other, with the total moulding about 
1.5 times the siding. 

Planking 

Smith developed his plank thickness, t, on the theory that 
deflection is constant and that load varies as the planking 
area, s. By simplification, (t/s)' varies as $ A. White 
this is sound theory, in practice the fact remains that no 
New England or Nova Scotia trawler has planking more 





e*<n. , 


in, In. "Standard from**" 


in. CwiR - 


e.em. 


.im. *8tondord froo* 


ckn. 
K 55 - 

1 50- 
45 - 


120- 
f 80- 


- 00 9-8 Moulding Siding * 0** 4 3 Sin. 
- 75*8-4 For olrw mtww: 
- 7-0 8-0 Section modirtu* 
- 5 85 siding R Moulding 1 


-27 
- 2 ^55- 

** ztl~ 


2000- 
ft 1800 - 


- 100x247 ^wwnf awing 
for olhor Metiont: 
-I75n22 StcHon ***** ^^... 


| S5- 

* SO -a 


|::: 

* 0- 

s 


-OR* 25 ' 
- 55 R 7 75 5 

-50H7-S8 ^ 
- 4-5 7-0 I ^ 


22 S ^ 

21 ^ 1 
-20 ? *"! 


^ I20O 
1000 ~ 
.00- 

00 


- I5020 
- 140 188 

- 125 IS6 | 
- 115 * 178 S 




ft SO - 






500 - 









4-Ot 8-58 jj 


18 w 




I00l5 - 


r 




5 


5 : 


400- 




* 15 - 


? 20 - 


-ssieie j. 


17 ; ~ 15 - 




- 8OKl5 ( 7 - 










0) *" I 


soo - 


* 


i 


f f9 " 


- S0 5 73 J 

a O 


i - 


250 - 


- 75* 145 

O 


5 .0- 


* 


^ 


t8 j| 10 _. 


100 







$ .OH 


- 2>888 12 


14 1 J 


180 - 


- 0x192 
- 55 128 


| : 


^ 

8 


- 2 0.5-0 


- 13 : : 


125 - 


- 50 1X8 


v 8 


! - 




8 - 


100 - 




4 


* 




12 * 







-TOO 
7* 
8O 
25 

578 
650 
828 

-800 f 
4T8| 

480 



880 
S25 

. ^o 



(A). Scantlings of frames (inch units) 



Fig. 148 
[155] 



(B). Scant lings of frames (metric writs) 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



34O- 



320- 
300- 



B 

1 200 -| 

*reoH 

* 

f 160 - 



M 



20 - 
100 - 




6 



9 10 ia 



100 



140 180 220 260mm 

Moulding of from of bitgt 

ovtr to* not to b l*i than ot I 



Fig. 149. Moulding of frame of deck and keel in relation to Its 
moulding at the bilge 



than 3 in. (76 mm.) nor less than \\ in. (38 mm.) thick. 
Examination of the examples shows that the space 
between frames (frame bay) varies only between 9 and 
12 in. (229 to 305 mm.)* In other words, the actual 
support of the plank depends very littfoon the size of the 
ship. However, the larger vessels obviously subject a 
greater load on the planking and its fastenings and it is 
therefore assumed that plank thickness varies as the N. 

There are a number of vessels between 110 and 120 ft. 
(33.5 and 36.5 HL) with 2f or 3 in. (70 or 76 mm.) plank- 
ing, and it is assumed that 3 in. (76 mm.) is the correct 
thickness for the median 1 15 ft. (32 m.) boat correspond- 
ing to N of 7.00. Another group of about 70 footers 
(21 m.) average 2 in. (51 mm.) planking for N of about 
5.00. 

Table 28 has been developed on this assumption atftt 
shows, in addition, the standard frame spacing associated 
with any N and plank thickness. 

It should be noted that all U.S. East Coast fishing 
vessels have their planking reinforced at the critical areas. 
A narrow belt of 1 in. (25 mm.) sheathing of oak or 
greenheart is carried along the waterline from the stem 
to the aft trawl gallows and it is extended dear to the 
rail below the trawl gallows. Further protection is pro- 
vided at the gallows by half oval strips or } in. (3*2 mm.) 
steel sheets. This sheathing is easily replaced when 
necessary and protects the planking from damage by ice, 
trawl doort, etc. 



Fig. 150 and 151 give scantlings for die deck beams, 
based on a similar analysis as described for the frames. 
Spacing is generally the same as for the frames and this is 
assumed in determining the deck thickness factor. 

Deck camber can be considerably greater than usually 
designed. For several years the writer has used a camber 
of between 0.4 and 0.5 in. per ft (33 and 41 mm. per m.) 
with satisfaction to the crews. 



There are two construction types: 

(a) double diagonal sheathing, with painted or treated 
fabric between the two layers and stiffeners on one 
side; 

(b) two thicknesses of tongue and groove planking, 
with the stiffeners (and insulation) between 

In very few cases is there any real attempt to make the 
bulkhead-skin connection watertight. Experience proves 
that it can be done, although at considerable expense. 
Vessels would undoubtedly be safer with bulkheads 
better than "reasonably watertight". It is doubtful if any 
wooden vessels would float for very long if seriously 
damaged, but to make them watertight in even a one- 
compartment class standard would, except in the very 
large ships, impair their fishing efficiency. 



cain. 

48 

o. 
544 

* 
f 40 

9 
O 

Z- 36 

i32 



24 



CO 



16 \6 20 22 24 26 ft. 

g 5 ^ b m 

0tom mo* of ship 

Fig. ISO. Section mntulU </<fo* btanu 



1156] 



SCANTLINGS SUGGESTED STANDARDS 



**q 

* 4i = 



M -i 



* tt - 

H 

f": 

r j 

i '*" 
i ..- 



Ml* 


14, I 14. 




,00- 


t-Ttt*4 




to - 


-t-ttxt-M 






-+OOxMt 




TO - 








- t-7t t>tt 




to - 
t to-, 


-frtOvTM 

-t*tt7>to 


! 


I... 


-KW.r.,4 


1 





-47txt7t 


r 


1 to- 


-4501448 


1 


i"- 


44 5 t-07 




9 

It 


9 ' , 

to - 


-4-OO57l 


\ 




- *7t if tt 




It - 







- 17 

- tt 
25 

14 
21 

- 22 

' r 

to ^ 

It 



It t 

17 



It 

m 



"5 tO 
t tt < 



I 

1 " 



ITOO 


-ITO*t4t 


itoo- 

ItOO- 


14ft it 14 


1400 - 


-ttOtttt 


1100 - 


-Itttttt 


itoo-: 




1100 ^ 
1000 ~ 


- 4tt07 


too 


-I40t00 { 

-IttMltl 1 


too - 






-It0ttt | 


| 700 - 


- Itfll7t j 


i "- 


..to.irt ^ 


S ! 


-Ittlt4 5 





4lO>lt7 





J 


r 400- 


lOftiltO 5 
-IOOI43 j 


aoo - 


tt19t 




- tOiUt 



WMi Ml., 



TOO 
t7t, 

tto 

tit 

-too 
trt 



47* 

< 

4to ; 

4 
418 

-400 
71 



(A). Scantlings of deck beams (inch units) 



Fig. 1 51 



(B). Scantlings of deck beams (metric units) 



To make the bulkhead tight at the planking, stop- 
waters are required in all the butts of the frame futtocks ; 
stop-waters in all the longitudinal joints on both sides 
of the bulkhead and caulking between the stop-waters; 
gaskets between planking and frame, and between 
ceiling and frame ; and caulking of the bulkhead chine log. 

Keels, stringen and other tagftudinab 

The suggested scantlings are based on mathematical 
averages worked from the "specimen" vessels and on the 
principal longitudinal member the planking. The siding 
and moulding of the keel are determined as follows: 

Keel siding is based on practice over many years 

Keel moulding is based on plank thickness, which 
varies as ^A, which again varies in relation to 
length 

In addition to contributing to the longitudinal 
strength, the keel is the chief contributor to drift 
resistance (when hauling in the net, for instance). 
Steel boats, even with a relatively small bar keel, do 
not handle nets as well as wooden boats with their 
relatively deep keels (Simpson, 1951) 

For details see heading: Determination of scantlings. 



Since World War II, glued laminated timber construction 
has advanced enormously and vessels up to 165 ft. (50 m.) 
in length have been completely laminated, and with a 
great saving in weight for, perhaps, greater strength. 
However, it is an expensive method and still rarely used 
except in military vessels. It is the author's opinion that 
material specifications are much more stringent than 
necessary (a laminated vessel requires more basic timber 
than a normal sawn construction ship), but even if much 
less material were used, the labour costs would be too 
high for fishing vessel construction. 



TABLE 28 

fitai^aiMl f ! mi IMII id iila uli tflklrfc~MfliM 


Frame spacing 


Plank thickness 


N 


in. 


mm. 


in, mm. 


4.00 


12 


305 


U 38 


4.25 


13 


330 


If 41 


4.50 


14 


356 


If 44 


4.75 


15 


380 


li 48 


5.00 


16 


406 


2 51 


5.25 


17 


432 


2i 


k 54 


5.50 


18 


457 


2 


57 


5.75 


18 


457 


2 


60 


6.00 


19 


483 


2 


64 


6.25 


20 


508 


2 


67 


6.50 


21 


533 


2 


70 


6.75 


22 


559 


2 


73 


7.00 


22 


559 


3 76 


7.25 


23 


584 


3j 


\ 79 


7.50 


24 


610 


3: 


83 


7.75 


25 


635 


3i 


86 


8.00 


26 


686 


3i 


89 



Timber grading 

There are numerous lumber association specifications for 
various species of timber, and each has its own grade 
specification covering the requirements for "select", 
"structural", "No. 1 common", "No. 2 common", and 
so on. The skilled shipwright will ignore most of these, 
knowing that in any given pile of timber of any species 
or any grade he can find both suitable and unsuitable 
ship timber, A crooked log that the millwright would 
pass over with scorn might be exactly the thing that would 
save the shipwright many hours of labour, as well as 
material, rather than produce an inferior item from 
straight stock. 

To quote from a memorandum prepared during World 
War II: "The actual piece of timber to be used must be 



[157] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



TAKE 



Aesistimc* to rot 

1 Uvecmk 

2 Gtwnbeart 

3 Juniper 

4 Cypnss 

5 Cedtr, white, yellow 

6 White oak 

7 Yellow bark oak 

8 Mahogany 

9 Grey oak 

10 Ycflow pine (dense) 

11 Douglas fir (dcnte) 

12 White June (Eastern) 

13 Sweet gum 

14 Hackmatack 

15 Mahogany (Philippine) 

16 Douglas nr (average) 

17 Larch (Western) 

18 White pine (Western) 



15 Larch (Western) 

16 YcOow pine (dense) 

17 Douglas fir (dense) 



20 Ash (white) 

21 Hm 

22 Red oak 

23 Maple, birch 

24 Spruce 



Ability to hold fastenings 

1 Beech 

2 Sugar maple 

3 White ash 

4 Yellow birch 

5 Teak 

6 Iron bark 

7 Live oak 

8 Oroenheart 

9 White oak 

10 Yellow bark oak 

11 Gieyoak 

12 Red oak 

13 Sweet gum 

14 Elm 



19 White pine 

20 Port Orford cedar 

21 Spruce 



Portability 

1 Mahogany 

2 Mahogany (Philippine) 

3 Cedar 

4 Oak 

5 Cypress 

6 White pine 

7 Spruce 

8 leak 

9 Fir 

10 Yellow pine 



Steam bending 

1 Ash (white) 

2 White oak 

3 Red oak 

4 Elm 

5 Beech 

6 Birch 

7 Yellow pine 

8 Cedar 



Mutability 

1 White pine 

2 Sitka spruce 

3 Mahogany 

4 DougfauTfir 

5 White oak 

6 Red oak 

7 Yellow pine 



satisfactory for the purpose intended and the specific 
inspection is more important than the general approval of 
any species or grade of lumber". 

All recommendations in this paper are based on the 
timbers in use in New England and Maritime vessels 
oak, fir and pine. There has not been time to relate these, 
in variable terms, to other timber more readily available 
in other regions. Table 29 might make comparisons easier. 



Plywoods of the marine waterproof type have been used 
in bulkhead sheathing, in crew quarters and in deckhouse 
construction. Hie builder should be cautioned that the 
weak point in all plywood as the edges, which should be 
weU painted just before being secured in place. 

There are many excellent formulae for plywood con- 
struction but, in practice, three thicknesses teem to be 
sufficient I in, (9,5 mm.) for interior sheathing; f in, 
(19 mm,) for bulkheads and house tops, and fin. or 1 in. 
(19 or 25 mm.) for deckhouse exteriors. Fig. 1S2 shows a 
practical ttiflener spacing. 



While not contributing to the immediate life or safety of 
the vessel, experience has proved that, when used in 
strategic places, a preservative of some sort greatly 
prolongs the life of the structure* Creosote and tar 
derivatives should not be used as they seem to affect the 
quality of the fish. Even brush coatings of copper 
naphthanates, and probably others, have been successful 
over a number of years. Needless to say, the coating 
should be applied after the final fitting and just before 
securing the members. Faying surfaces of frames, 
scarphs, heads and heels of frames, deadwoods and the 
upper surfaces of beams are especially benefited. 

DETERMINATION OF SCANTLINGS 

For a new vessel, it is only necessary to know the basic 
dimensions length, breadth and depth, as previously 
defined. 

1. Numerals: feet system 

3 /LOAxBxD 



y 



100 
F _ TB+D] 

F ~L~2~J 

metric system 



LOAxBxD 

2.83 
2.69(B+D) 

NxF 



= ? 
= ? 



0- D*ftoebn hi liwlw* 



pr*f*rr*4 by wrtlwx 



2000 

1200 
1000 

SOO 
SOO 

400 

SOO 


i 

i 
k 


1 120 

so- 
so- 

40- 


IOU 

SO 
60- 












\ _, 


. ,.77"" 




















H. . - 
















2 


















2 




SO 
40 

30 
















2 


. . 
































j^ 


' 


!?* 














/ 


, 














i 


] / 


it ^ ^ ' 




20 












- ! - 


tt 


4 ' - " 
















JCJl^ 














1 j 5 " 5 


T5*r 














Z, 


4 
















2 


1 
















7 2 ^ 


















y 


i ' 
























































di - - - 
















/ 


E 


















52 












S 

4 






















j 


r 




















f 




































* 


































































.--.- 


MM 




. , < M M 


" ! ! 'S 4 *'i'7 


1*0 20 


S-0 4-0 






S 4 S 7 S 16 IS SO SO 40 SO SO 100 



tllUllMtt 



Fig. 152. frtKtted *p***t of tUffmtrt 



1158] 



SCANTLINGS SUGGESTED STANDARDS 



2. Frame spacing and plank thickness: Select the stan- 
dard 'frame spacing (to the nearest } in. =12.7 mm.) and 
plank thickness (to the nearest J in. =3 mm.) from 
table 28. 

3. Frame dimensions: (a) Take out Z= section modulus 
of frame futtock for the calculated NX F from fig. 147. 

(b) Connect Z with standard frame spacing on fig. 148 
for feet or metres respectively and read dimensions for 
standard frame. Interpolate if necessary. If slightly 
thicker or thinner frame stock is more readably available, 
shift index line to suit and read new frame spacing. 
Return to table 28 and select plank thickness to suit. 

(c) Take out frame moulding at head and heel for 
selected frame moulding at bilge from fig. 149. 

4. Deck beams: (a) Take out section modulus per 
foot of ship's length for given B from fig. ISO. 

(b) Proceed as in operation 3, using selected frame 
spacing on fig. 151. In theory, the moulding of beams can 
be reduced as much as 20 per cent, at their ends. Siding 
can be reduced when beam length is less than |B. Increase 
siding 40 per cent, for hatches, partners, breaks, etc. 

5. Other scantlings: Are related to the thickness, t, 
of the standard planking. 

Keel, stem and dead wood: Sided 4 x t. Moulded 8 x t. 
For very full deckline, the upper part of stem may 
require an apron piece to give sufficient rabbet width. 

Keel shoe: 2\ to 4 in. (63 to 102 mm.) depending upon 
the length of the vessel. 

Keelsons: Sided and moulded 4 x t. 

Sister keelsons: Sided 3.2 x t. Moulded 0.8 x siding or 
2.56 xt. Not used in vessels shorter than 90 to 95 ft. 
(20 to 29 m.) LOA. 

Stern post and shaft log: l.Sxkeel siding, or 7.2 xt; 
not less than 3 x shaft diameter. 

Garboard stroke: 1 .5 x t ; 3 to 4 x t in width. 

Second garboard (when fitted) : 1 .2 x t. 

Clamps: Sided 1 .25 x t. Moulded 6.75 x siding (mould* 
ing in 2 or 3 strakcs). 

Shelf: Moulded 1.82xt. Sided 2.5 x moulding. 

Lock stroke: One of shelf members j in. (19 mm.) 
deeper. 

Lodger: Sided and moulded 2xt (fitted in vessels 
longer than 90 ft. or 27 m.). 

Bilge ceiling: Sided 1 .25 x t. Total moulding 13 x siding, 
should overlap butts of short futtocks at turn of bilge. 

Decking: White pine, generally same thickness as 
planking but not less than 2 in. (51 mm.). 

Rough deck: Spruce, } in. (19 mm.) in all vessels. 
Laid on working deck to protect structural deck (fastened 
with short nails). 

Bulkhead sheathing: Pine or fir, same total thickness as 
t of planking, laid in two layers. 

Bulkhead stiff eners: D 9 /10 x spacing gives a reasonable 
figure for Z. Moulding =^0.8Z, siding =0.6 M. 

Where D is depth of hull as before in feet 
Z is section modulus 
S is siding 
M is moulding 
Spacing in feet. 



Rail or bulwark stanchions: Sided and moulded same 
as frame at head; buried to lower edge of clamps. (About 
half the "specimen" vessels have one frame ftittock 
extended through the deck to form a stanchion. Better 
practice is to make the stanchion entirely separate a* 
above, secure it by two bolts extending through planking 
and ceiling. Such stanchions can be replaced without 
damage to the frame and the head of the frame is pro- 
tected from teaks in the deck caulking.) 

Following this recommendation, the scantlings of die 
three vessels in table 27 as built and as recommended 
have been listed in table 30. 

FASTENINGS 

Fastenings are more difficult to handle than the wood 
members, as definite mechanical stresses on ship joints 
are impossible to calculate. Again one must rely on what 
has proved sufficient. In addition, basic knowledge of the 
mechanical properties of various types of fastenings will 
be of help in developing reliable standards. A wooden 
ship is no better than its fastenings, and it is well to 
remember that an over-fastened structure is as bad as an 
under-fastened one and more expensive. A hole bored 
for a fastening is still just a hole, and subtracts just that 
much from the area of the timber, hence from its section 
modulus, etc. Fastenings placed too close together may, 
therefore, actually weaken the structure, as will too large 
fastenings. 

The proposed scantlings unquestionably allow for 
deterioration over the life of the vessel, and fastenings 
which may be weaker than the timbers connected mil 
then be sufficient for the deteriorated timber of some 
future date. 

Scarphs and fishplates 

Originally end joints were merely butted, then strengthened 
by overlapping pieces known as fishplates. In many 
places, the fishplate could not be used and the scarph 
was developed, and is still essential in longitudinal 
members of fishing vessels keels, keelsons, clamps and 
shelves and sometimes in topside planking and bilge 
ceiling, although it is of doubtful value there, in relation 
to expense. 

The standard scarph is of the nib-ended hook type, 
fig. 146, with a length of 5 to 6 times the depth of the 
timber and with all faying surfaces snugly fitted. Where 
keelsons, sister keelsons and shelves are built of several 
relatively thin members, a plain scarph may be used in 
the individual members. In many existing vessels these 
joints are simply butted, but this is not good practice. 

Metal fishplates are still used to reinforce the joint 
between keel and sternpost heel and in similar conditions* 
Here they are usually of the double fishtail pattern, set 
flush into the wood. 

TrecttaUs 

Treenails, throughnails or "trunnels", which ait various 
names for wooden dowels, used for all ship fastenings 



[159] 



PISHING BOATS OF THE WORLD; 2 ~~ CONSTRUCTION 

30 



VcwdNo. 



12 



LOA 






m. 
20.75 


B 




17.0 


5.18 


D 




8.83 


2.69 


N 






4.68 


F 






167 


NxF 






783 


Z for frames 






11.50 


Z for beams 






19.4 


Z for bulkhead stnTeners 






11.65 


Scantlings 
Plank thiokness . 


in. 
mm. 


As toUt 

% 


Proposed 

3 


Frame spacing 


in. 


16 


15 




mm* 


405 


380 


Frame, sided 


in. 


3 


2} 


moulded head 


mm. 

in 


76 


2 


rwne, 


14. 

mm* 


108 


108 


Frame, moulded bilge . 


in. 
mm. 


.2 


14$ 


Frame, moulded heel 


in. 


7 


71 




mm. 


178 


190 


Beam, space 


in. 


18 


15 




mm. 


457 


381 


Beam, moulded . 


in. 






Beam, sided . 


mm. 
in. 


4 


4 




mm. 


101 


101 


Keel .... 


in. 

mm. 


9x18 
228X457 


74x15 
190x381 


Keel shoe . 


in. 


3 


24 




mm. 


76 


63 


Keelson 


in. 
mm. 


8x10 
203x254 


7Jx74 
190x190 


Sister keelsons 


in. 










mm. 


. 


__ 


Sternpost and log 


in. 


17 


13 




mm. 


432 


330 


Garboard strake . 


in. 

mm. 


3 




Second garboard 


in. 










mm* 


__ 


__ 


Clamps 


in. 


24x16 


2|x 134 




mm* 


63x407 


60x343 


Shelf .... 


in. 


4x9 


3f x8( 




nun. 


101x228 


98x216 


Lock strake 


in. 
mm. 


3x5 
76x127 


24X4J 
63x114 


Lodger 


in. 










mm. 


._ 


__ 


BUge ceiling . 


in. 


24x30 


21x32 




mm* 


63x762 


60x812 


Decking 


in. 


9 


2 
51 



85.0 


m. 
25.9 


19.58 


5.96 


9.58 


2.92 




5.51 




212.5 


1,170 




17.5 




22.8 




13.8 


As built 


Proposed 


2J 


2i 


18 


18 


455 


455 


% 


i! 


5 

127 


,3 


,1! 


, 


9 


8J 


228 


210 


18 


18 


457 


457 


,3 


iS 


,a 


114 


9x20 


9x18 


228x507 


228x457 


31 


3 


89 


76 


10x8 


9x9 


254x203 


228x228 



3 
76 



2ixl6 

63x407 

4x7 

101 x 178 



24x48 
63x1,218 



JtS 

31 

85 



44x10 
105x254 

24x5 
63x127 



2Jx38 
73x965 



in. 



mm. 



20 

ft. HI. 

115.86 35 J 

23.75 7.25 

14.25 4.35 

7.26 
363 



x44 
70x114 



2 

70x121 



39,3 




34.3 




30.8 




As built 
3 
76 


Proposed 


20 


23 


507 


583 


5 
127 


,3 


,3 


146 


,5t 


:8 


10 


1 


254 


^ 


20 


23 


508 


585 


8 




203 


21 


5 


5f 


127 


146 


12x24 


124x25 


305x610 


318x635 


4 


4 


101 


101 


12x12 
305x305 


124x1 
318x31 


7x7 


10x8 


178x178 


254x203 


22 


22 


560 


560 


4 


4| 


101 


"I 


4^24 


31x26 


101x610 


98x660 


4x12 
101x305 


Sx 14 
x355 


4x5 
101 x 127 


4x64 
101 x 159 


6x6 
152x152 


Sx6i 
x!59 


3x48 


3}x50 


76x1,218 


98x1,270 


3 


3 


. 76 


76 


a 


i% 


_ 


95x159 



long before metal fastenings were developed, are occa- 
sionally still used, but it is believed that they have no 
place in modern, high-powered vessels. 



There have been many experiments to determine the 
holding power of various types of fastenings, such as 
wood screws and tag screws, cut ttafls and wife nails, 



spikes and drifts, both round and square, bolts, patent 
fastening aids, gjucs, etc. The following is a brief review 
of the results. 

A load may be applied laterally to the fastening, 
tending to break down the wood fibre and/or bend the 
fastening; or it may be applied lengthwise of the fasten- 
ing, tending to dniw it out of the wood. Most ship 
fastenings must resist a combination of the two loadings. 



SCANTLINGS SUGGESTED STANDARDS 



TAW* 31 



Type of fastening Lateral hading Loading in withdrawal 

Nails and spikes Pa-KaD"* P- 1,380G*/*D 

Screws P.~KJ> P2,850GD 

Lag screws Pf-KtD' P-1,800GV*D*/* 

Where P gives safe working loads in Ib. (to obtain kg. divide by 

22) 

G is the specific gravity of timber 
K is a coefficient based on specific gravity of timber 
D is the diameter of the fastening m inches (to obtain mm. 

multiply by 25.4) 



The basic factors that determine the holding power of 
any fastening are : the specific gravity of the wood and its 
moisture content; the diameter and penetration of the 
fastening; its relation to the grain of the wood (whether 
driven parallel or perpendicular to the grain), its fit and, 
of course, the type and material of the fastening. 

The common design formulae for the various fastenings 
are given in table 31 . Table 32 shows the required figures 
for the more common woods used in American ship- 
building. 

Pretoria* for fastenings 

For anything but the smallest nails, preboring reduces the 
tendency to split the wood and adds somewhat to the 



holding power. Boring should be done with a sharp tool, 
preferably of the twist drill type. A dull bit leaves a 
rough hole, reducing the contact surface and, therefore, 
the holding power. In heavy timber, holes are generally 
bored iV in. (1.6 mm.) smaller than the fastening. Better 
practice would vary the holes to suit the type of timber and 
the size and type of fastening. A bolt, for instance, 
needs only a slip fit, while a spike or drift requires a 
tighter fit as its holding power depends entirely on 
friction. 

For screws in lateral resistance, the holes in soft woods 
should be 85 per cent, of the diameter of the shank and 
root of the thread. In hardwoods, the ratio is 100 per 
cent. In withdrawal, the holes for the thread should 
be about 75 per cent, of the root diameter and 
about 90 per cent, of the shank diameter. Lubrication 
slightly increases the holding power of screws and lags, 
but has the reverse effect on nails, spikes and drifts. 

Plank fastenings 

The author made a series of tests in 1933. All fastenings 
were galvanized and sized as near as possible to a No. 14 
screw. They were driven into Maine oak frame stock, 
using the same size holes as if planking a vessel. They 
were all 2J in. (57 mm.) long and driven into the oak 
If in. (41 mm.). 

They were first pulled to the giving point; then an 
attempt was made to determine what holding power was 



TABLE 32 



Group Species 

\ Cedar, white 
Pine, white . 
Spruce, Sttka 

2 Cedar, Alaska 
Cedar, Port Orford 
Cypress 
Hackmatack . 

3 Fir, Doualas 
Larch, Western 
Pine, yellow 

Beech . 
Birch . 
Oak, red 
Oak, white 
Locust . 



0.32 
0.37 
0.42 

0.44 
0.44 
0.48 
0.56 

0.51 
0.59 
0.64 

0.64 
0.66 
0.66 
0.71 
0.71 



Kn 

1,040 
1,350 

1,650 
2,040 



K* 
2,520 

3,240 
3,960 
4,800 



1,800 
2,040 

2,280 
2,640 



G* 

0.102 
0.137 
0.176 

0.194 
0.194 
0.230 
0.314 

0.260 
0.348 
0.409 

0.409 
0.435 
0.435 
0.504 
0.504 



Or/ 

0.181 
0.225 
0.272 

0.292 
0.292 
0.333 
0.419 

0.364 
0.453 
0.512 

0.512 
0.536 
0*536 
0.598 
0.598 



0.058 
0.084 
0.114 

0.128 
0.128 
0.160 
0.235 

0.186 
0.267 
0.327 

0.327 
0.354 
0.354 
0.425 
0.425 



P n K B D/ t baed on depth of penetration not less than | length of nail or spike in soft woods and i in hardwoods 

P.-K^D 1 based on penetration of not less than 7 xdiam. of shank of screw 

Pi-KiD 1 based on penetration of 11 xdiam. of lag screw shank in Group 1; 9t xdiam. in Group 2; 8i xdiam. in Croup 3 and 7 xdiam. 

in Group 4 woods. 

The figures ace based on probored holes and with the fattening* driven perpendicular to the grain of the wood. When driven parallel to the 
grab, use 75 per cent of P for screws and lags and 60 per cent, of P for nails, spikes and drifts. ****** 

Kails, niket, drifts and screws should not be used in withdrawal condition in end grain. Lags may be so used, taking P at 60 per cent. 

These figures ait based on dry timber and bright steel fastenings. Fastenings driven into green timber have less holding power after the 



timber has 

GalvanTaod ffcstaomp have somewhat fast holding power when fint driven but, in moist timber as found in shipbuilding, after two < 



months, the holding power is i 



hat better than formulae 



shanks* 
two or throe 



[161] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



kit after the fastenings had been drawn J in. (6.4 nun.). 

Boat units gave suddenly *t widely different values: 
400, 300, 675 and 800 Ib. (ISO, 225, 310 and 360 leg.) and 
held very little; to 200 Ib. (0 to 90 kg.) at i in. (6.4 nun.) 
exit* 

Hatch nails started quite uniformly at 625 Ib. (280 kg.), 
gave gradually and held about a uniform 225 Ib. (102 kg.) 
at J in. (6.4 mm.) exit. 

No. 14 screws started at 1,200 to 1,350 Ib. (545 to 
610 kg,), gave gradually and held 450 to 500 Ib. (204 to 
226 kg.) at J in, (6.4 mm.) exit. 

Later some composition nails with a variety of comt- 
gations were tested under the same conditions and showed 
about twice the resistance as hatch nails in other words, 
about the same as screws of the same size. Still later, 
tests on bronze drift bolts of } in. (19 mm.) diam., with 
ratchet type grooves, showed the same excellent results. 

Another result of these tests was to confirm the repair- 
man's practice of replacing a fastening, once drawn, with 
a new fastening of slightly larger size. 



BoMiJ ?. sqoare faste 
Table 33 is taken from one of the many test reports 
concerning the holding power, in withdrawal, of round 
and square drift bolts. Note that the round and square 
rods of the same dimension (diameter or face), each in 
its own most efficient bored hole, have practically the 
same bedding power. However, the square rod weighs 
33 per cent more than the round rod and it is, therefore, 
more economical to use the round rod. The author's 
own tests showed the same thing, i.e., round fastenings 
are better and cheaper. 



It is sometimes overlooked that, on a weight basis, small 
fastenings have greater holding power than large ones, 



whether they be nails, drifts, screws or lags. This pro- 
perty is especially valuable where the length of fastening 
is limited. Also several small fastenings may be less 
liable to split the wood than, say, two large ones of the 
same holding power. 

Gahraoixed r. noa-ferroos fastenings 

The advantages or disadvantages are frequently discussed. 
It is well known, of course, that a copper nail has little 
holding power unless the end is "clenched". However, 
bronze screws have many devotees who speak vilely of 
galvanized fastenings. 

In theory, the non-ferrous metal is less siifyect to 
corrosion than galvanized metal and a good bronze screw 
can be driven harder than a galvanized one with less 
danger of breaking. However, non-ferrous metals are 
often chosen unwisely and two slightly differing compo- 
sitions can be spoiled by electrolysis. 

The life of hot dip galvanizing is sometimes amazing. 
The author has a planking spike, removed from an 
eighteen-year-old vessel with a yellow pine planking and 
oak frame. The plank was soft but the spike was hard to 
draw and, although its galvanizing is a bit discoloured, it 
is perfectly fit to be used again. Even much older 
fastenings are known to be in good condition. 

The galvanized fastening cements itself into the wood 
after a few months, and its holding power, in withdrawal, 
is then considerably greater than the formulae figures. 
Conversely, for a month or two, as the wood seasons, the 
strength is somewhat lower. In an explosion, in which 
some planking was blown off the top-sides of a vessel, it 
was noted that most of the planking spikes were still 
firmly planted in the oak frames. Their heads had been 
pulled through the mahogany planking. This also calls 
attention to another advantage of the hatch nail: its 
head is much larger than that of boat spikes. 



Diam. boned hole . 
Yellow pine partlkl to grain 
Yellow pine perpendicular to grain 
White otic parallel to grain 
White oak perpendicular to grain 

YttDW pine perpendicular to grain 



TABLE 33 

UHfattte heUiec power per tech [25.4 1 
lta.[2M.]4 

in. "/i 



Ib. 
kg. 

Ib. 
kg. 

Ib. 
kg. 

Ib. 
kg. 



200 
91 

375 
170 

617 
280 

1,200 
543 



Theobviota 



ing 



kg. 322 

efficient bored 

ftiom 

lapptiataltoto 



280 

127 

633 
288 

817 
370 

I f 778 
810 



777 
352 



344 
156 

781 
358 

1,033 
469 

2,500 
1,135 



222 
101 

400 
181 

867 
393 

1,133 
514 



675 
306 



Penetration 

14 in. 
(356 mm.) 

14 in. 
(356 mm.) 

11 in. 
(279 ram.) 

Ilia. 
(279 mm.) 



H&ysatiBasasis: 

M Mfft to round ftfrt^fi ftf% for pfaft^jM ftiofl fttrtn 



holding power a the iQuai* bolt in to 



H2] 



SCANTLINGS SUGGESTED STANDARDS 



TAKE 34 
wood screwi, practical | 



Practical length: 

Gauge 
Diameter D 

D* 

Root diam. 

Head 'diam, 

Practical length: 



Gauge . 
Diam. D 



Root diam. 
Head diam. 



11 in. (38 mm.) 



in. 
nun. 

. sq. in. 



in. 

mm. 

in. 
mill, 



0.125 0.138 

3.2 3.5 

0.0156 0.0190 

10.1 12.3 

0.098 0.105 

2.5 2.7 

0.2421 0.2684 

6.2 6.8 

li in. (38 mm.) > 

2 in. (51 mm.) 



0.151 
3.8 

0.0228 

14.7 

0.115 
2.9 

0.2947 

7.5 



0.164 
4.2 

0.0269 

17.4 

0.121 
3.1 

0.3210 
8.1 



2 in. (51 mm.) 






2* in. (63 mm.) 
10 




9 


11 


0.177 

4.5 


0.180 
4.6 


0.203 

52 


0.0313 
20.1 


0.0325 
21.0 


0,0412 
26.5 


0.129 
3.3 


0.141 
3.6 


OJ51 
3.8 


0.3474 
8.8 


0.3737 
9.5 


0.400 
10,2 



21 in. (63 mm.) 



3 in. (76 mm.) 



3J in. (89 mm.) 



in. 
mm. 

. sq. in. 
sq. mm. 

in. 
mm. 

in. 

mm. 



12 

0.216 
5.5 

0.0467 
30.1 

0.161 
4.1 

0.4263 
10.8 



14 

0.242 
6.2 

0.0586 

37.8 

0.178 
4.5 

0.4790 
12.2 



16 

0.268 
6.8 

0.0718 
46.3 

0.200 
5.1 

0.5316 
13.5 



t j 


A if* (\{U mm \ 




18 


20 


24 


0.294 

7.5 


0.320 
8.1 


0.372 
9.5 


0.0864 

55.7 


0.1024 
66.2 


0.1384 
89.5 


0.226 
5.7 


0.245 
62 


0.270 
6.9 


0.5842 
14.8 


0.6368 
16.2 


0.7421 
18.8 



About two-thirds of the screw length is threaded. For best results the shank of the screw should be started into the foundation 
Lubrication makes easier driving with no effect on holding power. 



Resistance to withdrawal in Ike direction of driring 

Drifts have the least resistance to withdrawal in the 
direction that they were driven, some tests giving about 
60 per cent, of the resistance shown in retraction. For- 
tunately, the head formed on long drifts during the pro- 
cess of driving greatly counteracts this difference. Short 
drifts should have small heads formed before driving. 
Spikes and drifts should be driven at least twice the 
thickness of the fastened member into the foundation 
member. 

In practice, when drifting tiers of members such as 
keelsons, through floors to keels, and edge fastening of 
ceiling, damps etc., the fastening is driven through the 
fastened member, the adjacent member and at least 
two-thirds of the depth into the third member. The hole 
boied through the fastened member should be little 
tighter than a slip fit 



short tapered cones, with the end little smaller than the 
bored hole, see fig. 153. A long taper, either in a cone or 
chisel point, is likely to split the wood, and the length of 
the point has no holding power. The tests covered long 
chisel-pointed square spikes, and it was found that in 



Fig. 153. A: *hip spike, B: hatch 
nail. A and B have the same hold* 
tnf power per wit lenfth ofpene* 
tratton, however fofafriMrf Mtift 
nails B weigh about 70 per cent. *f 
the galvanized mike. The bearing 
ojwofthcheado/Atsoitly" 
cent, of that of M. 7m 

apt lo ipttr the wood or to At 

turned oy hard /train tnan tne 

ctoselpotxtofA 



****** -" - t u II 

The author's toft* confirm the general experience that the * 
pointed end of spikes and drifts should be in the form of 

1163] 




FISHING BOATS OP THE WORLD: 2 CONSTRUCTION 



yellow pine, particularly, the long taper would catch 
against the hard grain, carrying the spike so far to one 
side that an arc of the bored hole was untouched This 




Fig. 154. C: hanger bolt, D: lag 
screw. Whtie the holding power of 
D is much greater than that of 
either A or B, the bearing area of 
theheadof&ia79percent.ofA 
and only 40 per cent, of B. A 
washer mint be used under the 
head when bearing on wood. D 
should not be used when its fre- 
quent removal is foreseen. C 
should be used for holding metal to 
wood where adjustment or replace- 
ment is foreseen 




the fhflnV of the name diameter and depth as the 

For the threaded portion the hole should be equal to the 

length of the threaded portion. The guiding figures are: 

In oak or similar hard woods- 65 per cent, to 85 per 

cent* of the shank diameter 
In Douglas fir or Southern pine 60 per cent, to 75 per 

cent, of the shank diameter 
In pine, cedar or spruce 40 per cent, to 70 per cent. 

of the shank diameter 
The larger percentages apply to the larger sizes. 

If the use of lag screws in end grain is unavoidable, then 
60 per cent, of the values for P should be used. 

Lags should not be driven nor even started with a 
hammer. 

Where it is possible that a fastening may be removed, 
such as in realigning an engine or replacing a damaged 
fitting, hanger-bolts should be used instead of lags, 
fig. 154C. Once withdrawn, a lag should be replaced with 
a larger size. 

Brits 

Through fastenings may be made by riveting over clinch 
rings or by threaded nuts the latter being much the 
better method. Bolts should be galvanized after the 



not only destroys holding power, but could be a source of 
leaks. 

A short chisel point is the next best to the blunt cone. 
It should be driven with the chisel edge across the grain 
of the member most likely to be split. 

Wood scjeiw 

Table 34 shows the practical limits of gauges and lengths, 
particularly for hard woods and with properly sized 
prebored holes. Nickel-bronze screws of larger size can 
be used without danger of breaking. Screws should not 
be started with a hammer and should not be over driven. 
Power screw drivers are prone to this error unless in very 
skilful hands. While screws are often used to draw 
members together, this is bad practice clamps do a 
better job. 

Screws should be driven to full depth of the thread 
into the foundation member for best results in with- 
drawal, and slightly more for lateral strength. 

Screws are said to damage the wood slightly for a shaft 
distance and should, therefore, in soft wood be spaced not 
less than i in, (12.7 mm.) across the grain, nor less than 
1 in. (25.4 mm.) along the grain, when driven perpen- 
dicular to the grain. For No. 10 and larger screws, these 
figures should be doubled, and for hard wood another 
} in. should be added to all figures. A slightly smaller 
spacing may be used when driven parallel to the fibres. 
Spacing from the edge should be not less than 3 diameters . 

Lag screws 

Lag screws, generally, may be treated as large wood 
screws, fig. 154D. Preboring should provide a hole for 



020 O90 040 0*0 O40 0-7O 




J 



Hg. 1SS. HMIiy power of Itftcrewt 



11441 



SCANTLINGS SUGGESTED STANDARDS 



threads are cut, and due allowance should be made for 
this when cutting the threads. The threaded nut, par- 
ticularly when fitted over a heavy washer, can be used to 
draw the members together and to take up the slack due to 
inevitable shrinkage. Clinch rings can do neither very 
well, and a loose clinch ring has no value. 

Bolts should be of the carriage or T head type, with a 
square under the head to prevent turning. 

The bored holes should provide an easy driving fit. 

Where fittings are bolt fastened, the washer should be 
in one plate, taking all the bolts wherever possible. This 
makes the fitting almost one with the wood to which it is 
fastened. 

There are many tables giving strength values for bolts in 
various conditions, and it is not a subject to deal with in 
detail in this paper. Generally, by using heavy and large 
washers, bolts can be stressed to the safe values of the 
metal and the thread root diameter. 

Fittings and foundations 

Chainplates, cleats, pad eyes and machinery should be 
secured by through bolts wherever possible. Wherever 
lags or screws must be used, they should have the 
maximum length, and the values of P in the formulae 
for lateral resistance can be increased by 25 per cent, 
when the fastening is parallel to the grain. 

Timber connectors 

Timber connectors in a variety of shapes and patents and 
much used in land structures, greatly increase the lateral 
strength of timber joints. The author made extensive use 



TABLE 35 



Tack bolts for keel and keelson 

members, scarphs, etc.: Keel siding x 0.085 

Frames to keel (2 drift bolts): Siding of frame member x 0.1 75 
Keelson, through frames to keel 

(2 drifts) : Siding of tome member x 0.216 

Sister keelsons through keelson; 

sister keelsons through frame 

to garboard : Moulding x 0. 1 

Garboard to keel (alternate 

frame bays); garboard to 

frames: Thickness of garboard x 0.1 71 

Clamps to framesU bolt, 1 spike): Siding of frame x 0.142 
Ceiling to frames (1 bolt, 1 spike): Siding of frame x 0.135 
Lodgers; to frames and beams: Largest dimension x 0.1 5 
Beams to clamps : Siding of damp x 0.25 

Planking to frames (2 hatch nails 

to frame) : t (plank) x 0.18 

Length - 2. 4t if bunged, 3t if flush 
Deck to beams: Diam. =tx 0.125 

Length*** 2t 
Ice sheathing to planks : Long enough to penetrate $ to f 

main planking 
[measurements in inches] 

Notes 

All fastenings should be galvanized, preferably by hot dip. 
Round plank fastenings (hatch nails) are much more effective than 

square spikes. 
Bolts should have washers under both head and nut wherever 

possible. Heavy drop forged washers are more effective than thin 

punched washers. 
When it is necessary to draw a fastening, the replacement should be 

A to t in. (1.6 to 3.2 mm.) larger. 



Cyprtss factor HOC 
White pint t23 
YftDow pint 2 25 
Oak 2-69 



kg. 


Ib. 








**r* 


















9flATl 




















/ 




900- 


UUU 




















/ y 






ion A 


















/ 


f/ 




800- 




















/ s 


/ 






1 ft Aft 
















s 


/s 






700- 


















SS 




*a6 






1 4ftft 














/ 


// 




14 




<o 600- 
















// 




* 






1 


1 5ftft 












/ 


//* 


W 


M2 








i cvv 












/./. 


rS/ 










OOW 


1 f\f\f\ 










y/ 


^S/S 


y/ 










gL f\f\ 


\ UOU 








ta2f 


//> 


o^J 


r 14 


, 








4OO - 


A/WH 








iki?fi 


^Vf 


s*S 


/" 










a 


8OO 








,/ 


^^ 


r^/ 


No. 


ft 








& 300- 


SVA 






fetft 


t# 


y <> 


^ S 














6OU 






* 


ry 


r - 


r* 


N&6 










200- 


4ftft 








^r 


s^^> 


^ 
















, 


_lfj 


y^ 


^ 

" 
















100- 


9 ft ft 




^ 


^^ 






















4 


$p 

^ 


P^^ 






















1 


























> 


1 




i 


\ 


\ 


\ 


4 


f 


s 


Hn. 




c 


> 


20 


4 


K) 


60 




BO 


1C 





120 


mm. 



Lftngtti of terow 
Fig. 136. HoMto? power of wood screws 



of them during World War II to join members of keels, 
keelsons, shelves and frames of a hundred or more 
salvage vessels, subject to extraordinary stresses in their 
day's work. Some of these vessels, almost unstrained, 
survived experiences that broke up vessels of normal 
construction. 

Connectors of the split ring type have been used in keel 
and keelson members of some of the larger U.S. wooden 
trawlers. However, the double assembly required makes 
their use rather costly and probably unwarranted for 
smaller fishing vessels. Further information can be found 
in the literature. The holding power in shear of a 4 in. 
(102 mm.) split ring connector in conjunction with its 
} in. (19 mm.) diam. bolt is about S times that of the bolt 
alone. 

Glue joints 

The use of laminated wood and glue fastening in vessel 
construction is rapidly advancing in many countries, 
having started about the end of World War II. Glues in 
numerous varieties, and with almost unbelievable proper- 
ties, are available. Even metal surfaces can be "stuck*' 
together with ultimate tensile strength of upwards of 
5,000 Ib./sq. in. (350 kg./sq. cm.). 

The method had its inception, ostensibly, in an effort 
to conserve the ever-increasing scarcity of timber. How- 



FISHING fcOATS OF TfrE WORLD: 2 CONSTRUCTION 

ever, material specifications are so stringent that 165 ft. production. Nevertheless, the progressive builder will do 

(SO at) non-magnetic mine-sweepers built for the U.S. well to keep informed of developments in this field. 
Navy, although very successful vessels, are said to 

require some 20 per cent, more standing timber than if Determination of fastenings 

buih in the orthodox manner. From the vessels listed, plus other partially complete 

The equipment for satisfactory gluing is extensive and data available, the mathematical "average" has been 

expensive and labour costs are rather high, so that this established and "standards of practice'* proposed in 

type of construction is as yet not economic for commercial table 35. 



166] 



SCANTLINGS DISCUSSION 



MR. J-O. TRAUNG (FAO, Rapporteur): The relevant papers 
concerned with scantlings were Gunner's paper on surf boats, 
Beach's on small outboard motor craft, and Ringhaver's on 
mass production of shrimp trawlers. 

Gurtner adopted bent frames in a small boat which is 
subjected to great stresses when landing on a beach because 
bent frames for that purpose give stronger construction for a 
given weight. Beach's paper is interesting in that it shows how 
boats can be made today with marine plywood, especially in 
countries where the cost of labour is high. Ringhaver's paper 
on shrimp trawlers shows bent frame construction but much 
lighter scantlings than given in Simpson's recommendations. 
This shows that when weather conditions are less severe the 
boats can be built lighter. 

Good boatbuilding practices 

MR. H. I. CHAPELLE (U.S.A.): Bent frames were now more 
economical and the sizes and types of North American fishing 
boats made this type of frames highly desirable. 

It was his belief that bent frames should be thin and wide, 
rather than square in cross section, to avoid damage to the 
grain in bending or over steaming and resulting brittleness and 
breakage. Red oak had proved reasonably satisfactory. Green 
or nearly green stock seemed to be effective, steaming and 
caulking apparently preventing rot. 

Floors ought to be placed on top of bent frames. Floors 
should have two long arms made of sawn plank on top of the 
frame, bolted at keel centre-line and joined by a common 
plank floor timber. They should be spaced every third or 
fourth frame and common short plank floors, if necessary, 
fitted on top of the intermediate frames. Experience had 
shown that this produced a strong and rigid bottom. 

Hard bends in the frames require lamination, or splitting 
the frame. Split frames to be secured by the plank fastenings. 

Stiffening of the topsides should be done by the use of deep 
shelves at least in the midbody and by hanging knees at central 
points of support. Locking knees might also be used 
occasionally. 

Frame spacing of the wide, thin bent frames may be greater 
than with square frames of the same cross-section. The wide 
frame gives better planking support by its greater bearing 
surface. 

He considered square fastenings, boatnails and spikes, 
superior to round ones, but they require great care in boring 
and driving. 

Rot was an important problem. Formerly, impregnation 
with creosote or copper naphthalate was recommended but 
now a simple brush treatment was used to sterilize the timber 
and this seemed to destroy fungi and add 5 to 7 years of life 
at small cost. Salt was a very useful preservative, placed 
outside the clamp on stops inserted between frames. This 
could prevent mould and fungi for a very long period, 10 to 
15 yean. Experience suggests that it is best to build boats of 



timber native to the area in which a boat will be used, as 
native timber appears to have some greater resistance to local 
fungi, compared to imported stock. 

Ventilation was very important but very difficult to accom- 
plish. Deckwood should be formed to avoid pockets, creo- 
soted if possible, and openings in bulkheads left for ventila- 
tion. Openings in ceiling and framework for this purpose were 
necessary. 

Painting the bilge area should never be done in a wooden 
boat, it encourages rot in the vicinity of frames, floors and 
even in the planking* 

Rail stanchions should never be part of or joined to the 
frames. It is practically impossible to prevent breakage of 
stanchions sooner or later. They should be placed between 
the frames and fastened to the damps from inside the hull. 
This makes replacement easy and prevents or delays rots in 
topside timbers or framing. 

The use of steel engine bedcaps is desirable, particularly 
with a heavy engine. Strapping and fish plates are useful. To 
prevent condensation forming and rot resulting these should 
be bedded in tar or asphalt and tarred felt or paper. 

U.S.A. rides and experience 

MR. H. C. HANSON (U.S.A.): Loadline scantling rules were 
established primarily for large cargo ships of steel construe* 
tion. Most of these vessels have a full square midship section 
and a parallel mid body. The U.S. Coast Guard and ABS 
rules state that : "Where the frame obtains additional strength 
from the form of the vessel, due allowance is to be made to 
the value of the coefficient.** So some thought was given to the 
shape of the hull when the rules were written, but no con- 
sideration is given in actual practice. Therefore, such rules 
work to the disadvantage of vessels other than of the square 
section type. 

Applied to smaller wooden vessels, such rules become very 
unfair as most wooden vessels, especially those with smaller 
dimensions, gain their greatest strength through their deadrise, 
which makes the lines of the vessel fore and aft fairer, rising 
quickly towards the ends. There are seldom more than two 
to four identical frames. Such a hull shape is much stronger 
than one with a flat bottom. He had obtained measurements 
of the hog in the keels of various vessels, which showed that 
the flat bottom craft invariably hogs, whereas the vessels with 
a deadrise remain straight for many years. One vessel 
operating now is 60 years old and had retained her original 
shape. Any rule that does not take into consideration the hull 
shape is not correct according to his experience and judgement. 

Other construction features are necessary for the wooden 
vessel to keep its shape for years. The steel vessel relies on its 
shell plating for its longitudinal strength; on its floors for its 
transverse. The wooden vessel for cargo purposes and for 
really heavy weather relies for its fore and aft strength on 
strength members, such as the bilge ceiling, side ceiling* 



[167] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



damps and shelves and bulkheads. It does not depend on its 
planking, although the planking, if properly fitted, will give 
considerable longitudinal strength when new. The planking 
to give strength must fit wood to wood, and to do this small 
caulking seams must be used. 

During World War I much timber was wasted by improper 
use in the tremendous wooden ship building programme. 
Some seemed to believe that merely by putting timber into the 
vessel strength would be added. If a little more time and 
thought had been spent during design, much of the natural 
resources would have been saved and wooden ships would 
have had a better standing. This was also true during World 
War II, but to a much lesser extent because there were not so 
many large wooden vessels built. 

At the end of World War I, some designers used double 
diagonal planking inside the regular planking to provide 
greater longitudinal strength. However, nothing came of it. 
During World War II, the Navy used this system in the 
wooden minesweepers. These vessels were not designed for 
carrying cargo and had no inside strength. They were of bent 
oak frame construction; they had deadrise and good shape, 
but were not strong enough for carrying cargo. Once these 
vessels are recaulked in the customary method, they will 
gradually lose their original strength and are not to be com- 
pared with orthodox methods of wood construction with the 
strength built into the ceiling. 

One of the older vessels built along this order was the 
Roosevelt, built especially for Arctic exploratory work. The 
hull had curvature all ways, fore and aft and transversely. The 
construction was by the double planked fore and aft method 
and the vessel was apparently designed for bruising against 
the ice rather than for great longitudinal strength. Nominal 
ceiling was used, but the vessel held her shape to the very end 
of her career, due undoubtedly to the hull shape. She was 
about 35 years old when wrecked. 

The tuna vessels built on the Pacific coast are an example 
of the vessels holding their shape due to hull design, in spite 
of the fact that many were not properly built in terms of good 
ship construction. They could be called satisfactory as most 
of them did not hog at all. As long as they were used for tuna 
work and retained their many watertight bulkheads, they were 
satisfactory, but without bulkheads they could not be called 
good vessels. Only in rare instances were they built with heavy 
long floors. 

It is very important when building a wooden vessel to be 
careful when selecting lumber. With rot-resistant woods, 
such as yellow cedar, few troubles will arise. If one is unable 
to obtain rot-resistant wood in quantities to build all the upper 
part of the vessel, then it should be used in those members 
where rot mostly occurs, so that if a repair job is necessary, 
Die main frame can be saved and repairs be made economic- 
ally. The important members that are usually subject to decay 
are the frame heads, the rim timbers, covering boards around 
the frame heads, and above the rims. In fact, wherever fresh 
water leaks occur, rot will commence. Deck planking is 
easily replaceable so it is not so important to have rot-proof 
woods there, but the house coamings are susceptible. 

Years ago fir was easily obtainable near the salt water, so 
cutting in winter was easily done. However, in later years, 
say, since World War I, cutting of timber spread away from 
the sea and is now largely done in the summer. This means 
that the togs are never stored in salt water but only in fresh 



water, for some period. If they do, they will have a good stan 
towards decay even before being cut into lumber. Also, since 
the logs are cut in the summer, the sap is up: winter is the 
best time for cutting trees. 

Yellow cedar grows at the snow line and its annular grain 
set-up is very narrow, showing its fight to live. So in the 
selection of lumber for boat building, it is always best to use 
the logs with the very narrow annual rings. Second growth 
timber should be avoided as much as possible as this has not 
attained mature growth, usually having the wide rings. 

AH lumber used should be free from large knots, sap, pitch 
pockets, decay or other imperfections that would render it 
unsuitable for the wood building purposes. All lumber should 
be air-seasoned. As a minimum, the keel, keelsons, dead- 
woods and frame timbers should be seasoned for from 30 to 
60 days; the ceiling, beams, bilge stringers, shelves and clamps, 
waterways for from 60 to 90 days; the topside planking, 
beams, coamings and the like from 90 to 120 days. Spacing 
sticks should be used so that air can circulate all around 
timbers and the ends protected so that they are not sun or 
air checked. 

Usually it is best to use ironbark for the stem, gripe, fore- 
foot, stern post and the like, and in case of a cruiser stern, the 
lower rim should be of ironbark. 

Oak is by its very nature full of moisture and it takes a long 
time to dry, so it is very difficult to determine the life of this 
wood. If oak comes in contact with other woods, it induces 
decay through the moisture from it. Mr. Hanson had had 
success with steam-bent frames, by painting the frame with 
preservative such as cuprilignum before steaming, but the oak 
was fairly dry when used and did dry after being bent to shape. 
This type of frame was used for minesweepers. 

Preservatives should be used on all faying surfaces, between 
the ceiling edges, the back of ceiling facing the frame, face of 
frame when dubbed, faying surfaces between frames, back of 
planking, and so on. Preservatives should coat the outside of 
the wood as well as penetrate it. Any preservative, such as 
creosote, that is placed over the wood forming a coating, is 
harmful as moisture will collect under this coating and rot will 
occur. 

Caulking 

One important aspect in the construction of wooden vessels 
that is guided by the "hand-me-down" system is in the caulk- 
ing of the vessel. Reference can always be found in the old 
publications and writings relative to the use of "hawsing 
beetles'*. This is a large wooden maul with a handle about 
3 ft. (0.9 m.) long. The Navy Wooden Boat Manual 250-336 
includes it as recently as 1948 as a guide. After the regular 
caulking has been done by hand, the seams are then gone over 
by two men, one with a hawsing iron and the other with 
powerful blows to set the caulking up. Mr. Hanson long ago 
had come to the conclusion that wherever possible the use of 
this hawsing beetle should be prevented. It has been his creed 
to see that in all the vessels that he had to deal with, whether 
in the design or the building, the seams should be made as 
small as possible and only hand caulking used. The reason 
for this is that the caulker has better "feel" and coordination 
with the smaller caulking mallet and, because of that, can 
place the oakum and cotton in the seams more evenly, 
throughout the length of the seam. This is very important 
because when driving with the large beetle this simply cannot 
be regulated. AH Wows by this method are different: one may 
be 50 Ib. (23 kg.), the next 60 Ib. (27 kg.), and then one may be 



[168] 



SCANTLINGS DISCUSSION 



75 lb, (39 kg,), and wherever the heaviest blow is made, it 
spoils the work done before and the stage is set for seepage 
into the seams. This would not be so bad under water, in salt 
water, but on deck where fresh water comes and goes, it will 
not be long before rot starts. This is one of the main causes 
for maintenance costs in wooden vessels. He had seen the 
caulkers at the drydocks immediately take this beetle and start 
on the stern posts and exposed deadwoods. They will drive 
the hawsing iron up to the hilt into the seams and spread the 
seams sometimes as much as I in. (19 mm.) wide: this, in a 
seam that was wood to wood when built, just naturally destroys 
the vessel in time. 

Mr. Hanson for years had insisted that the seams in any 
boat of his design be made as small as possible, and on hand 
caulking only, making the planking wood to wood at least 
half the depth. This he had adhered to, and vessels such as the 
Penguin, Brown Bear, Lester Jones, Patron, Northwestern, and 
many others, never had to be caulked. The only reason that 
they finally came to the caulking phase was because of the 
"beetling'* process commonly used in the drydocks. This 
creates additional work for the drydocks, but he thought that 
this method was used only because that is the way they have 
seen it done and continue to do it. 

Farther U.S.A. practice 

MR. H. I. CHAPELLE (U.S.A.): He agreed with Hanson in 
practically all matters, particularly so where deadrise affects 
strength. Longitudinal strength is lacking in many wooden 
boats today. Improper construction design causes this. 
Diagonal planking, or diagonal strapping of the hull, are 
rarely seen and are considered costly and, with the introduc- 
tion of steam bent frames in large fishing boats in the East 
coast of U.S.A. thought was given to the design of structure 
particularly in this matter of longitudinal strength. With 
regard to the Roosevelt he believed she originally had longi- 
tudinal strength members that were removed after her useful- 
ness in Arctic work was ended. She was very carefully designed 
by experienced shipbuilders, he was informed. 

The Woods Products Laboratory, U.S. Department of 
Agriculture, had informed him that excessive steaming or 
boiling of steam-bent oak frames produces brittleness in some 
degree and that use of wood preservative before steaming is 
not recommended. To avoid the first it is necessary to use 
young and not thoroughly seasoned oak, apparently. 

Over caulking is very common in repair yards. A new 
vessel ought to have little or no driven caulking but U.S. 
yards seem to have lost the skill in fitting required, to a 
steadily increasing degree. 

A great deal of Western Fir has been used in the East of 
U.S.A. since the beginning of World War II. It is a strange 
thing reconsidering the good record of this timber on the 
West Coast that Western Fir has gained a poor reputation in 
the East. Extensive and rapid rotting has occurred, obviously 
far more destructively in East coast boats than in Western 
craft. There was much trouble with Eastern built fir vessels in 
the Army and there has also been so in more recently built 
Eastern boats in spite of the use of preservatives. A similar 
situation has been found in boats built of materials of the 
Canadian Maritime Provinces when Canadian built boats are 
brought to Southern New England and to the Middle Atlantic 
States. These boats were of superior workmanship and 
material was carefully selected, but rot was both rapid and 
far-reaching. Mr. Chapclle therefore agreed with the Depart- 
ment of Agriculture suggestion that there are advantages in 
employing timber native to the area in which a boat is used. 



Australian practice 

MR. ARTHUR N. SWINFIELD (Australia): From what he could 
gather, overseas construction does vary quite a deal from usual 
Australian ideas of construction; but so does the type and 
species of timber, along with climatic conditions. These last 
two factors dictate the builder's approach to building com- 
mercial vessels hence no doubt the difference in design. 

Almost every wooden commercial vessel in Australia is 
built of hardwood, with the possible exception of planking and 
decking; these could be of Oregon, but in many cases are of 
medium hardwoods. The term "hardwood" relates to many 
approved types of eucalyptus, most of which weigh in the 
vicinity of 55 to 65 Ib./cu. ft. (880 to 1,040 kg./cu. m.) at 
12 per cent, moisture content. These timbers are naturally 
heavy to handle, hard to work, and hard to bore for fastening. 
However, they "take" steam well, do not crush under 
fastenings, and produce very strong and durable frame work. 

For many years steam-bent frames have been used exclusively 
so that it is unusual to see a sawn frame vessel at any time- 
regardless of dimensions. Laminating becomes accepted 
practice in any frame over 1 1 in. (35 mm.) thick, depending, of 
course, upon the sectional shape of the vessel. 

Boat builders prefer bent frames of flatter section to those 
used overseas. His personal conclusions are that, from a 
practical angle: 

A wider timber (frame) gives more room for reeling or 
staggering of fastenings 

In spite of the fact that its modulus is reduced (by its 
very shape) it loses less strength from boring of fastenings 
than would a narrow, thicker frame 

Collapse and fracture are not so prevalent at significant 
points of stress 

Lamination is always reverted to as required and presents 
no problem 

Referring to the general construction of a wooden vessel, 
drift bolts are seldom (if ever) used in any vessel; screw bolts 
are always preferred: bilge ceiling as known overseas is not 
used; bulkheads are regarded with seemingly greater impor- 
tance; edge fastening of garboards is rarely used; planking is 
thinner; bent frames are closer spaced; all fastenings are 
copper and are through fastened. 

Stringers occur at "floor" tops, bilge, and half way between 
bilge and clamp always "on their flat" and through fastened 
with copper screw bolts through planking and bent timbers. 

It is in the last remark that he found a most significant 
detail when considering flat sectioned frames as against a 
deep or square sectioned bent frame. So often does one find 
a bent frame practically cut in halves by the very fastenings 
that go through or into it so that unless the frame is made 
wide enough to take the actual fastenings (stringers or plank 
fastenings), all talk of modulus becomes mere theory. 

How often does the repair man lift a stringer (particularly 
in the way of the bilge) only to find the bent frames fractured 
just where they are most needed, and this very often is due to 
the very fastenings themselves. True enough, a vessel is as 
strong as her fastenings/ but fastenings can in truth, by their 
very size, prove weak links, particularly in deep sections. 

All plank fastenings are copper through fastenings, either 
riveted (rooved) or turned over. A combination of both is 
sometimes used. Square copper nails are used exclusively, and 
all nails are driven through bored holes. 

Another aspect of design, deserving special consideration, 
is that relating to the fastening of the covering board which to 
his way of thinking is always a possible source of trouble. So 
often one notices the top strake used as the "chopping block" 



[169] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



TABLE 36 



Volumes in cu. m. for Iin7(3.28 It.) lengthmidship section 






CLASSIFICATION 








New England 


Burm Veritas 


Danish 


Swedish Newfoundland 


HansOtl',\ 






irtwlers 


(Franc*) 


Regulations 


Regulations Rules \ Scantling* 








(no regulations) 










1 


Boat 


Timber 


Simpson's 


























No. 




proposal 




Percentage 




PfrCtntttte 


Percentage 




Percentage 








of 




of 


of 




or oi of 






As built 


difference 

from 


As built 


difference 
from 


As built 


difference 
from 


As built \ difference As built i difference At built difference 
' from ' from \ from 










Simpson's 




Simpson's 




Simpson's 




Simpson's j Simpson's 


Simpson's 






\ 


\ 












6 


Oak 


1.120 


1.250 


+ 11.6 


1.376 +22.8 


1.570 


+40.0 


1.470 


+ 31.2 1,368 1+22.01 


1.314 -17.45 


20.75 m. 






i 


















f*j__ 
pine 


0.260 0.294 + 13.1 0.340 


+30.8 


0.352 


+ 35.4 


0.336 


+ 29.2 


0.293 


+ 12.7 0.260 Nil 








i 


i 










i Oak and pine 






! 










i 


i conv. to oak 1.336 


1.495 


+ 11.9 1.659 +24.2 


1.863 +39.5 


1.750 


+ 30.09 


1.612 + 20.7 


1.531 -14.6 








l 
















12 


Oak 1.564 


1.556 


- 5.1 1.960 


+25.6 


2.242 


+43.7 


1.970 


426.3 


2.122 


+ 36.0 


1.910 -22.2 


25.9 m. 






























Fine 0.334 0.334 


Nil 


0.456 +36.6 


0.388 


+ 16.2 


0.450 


-f34.8 


0.364 -f 9.0 


0.374 -11.4 


1 














1 


; Oak and pine 
















i 




conv. to oak 1.842 


1.834 


- 0.4 


2.340 +27.6 


2.565 +39.5 


2.345 


+ 27,6 


2.425 


+ 31.9 


2.222 -20.6 


20 


Oak i 2.810 


2.644 - 5.9 


2.810 


Nil 


_ 





3.460 


+ 23.1 


3.280 -16.7 


35.3 m. 


























Pine 0.556 


0.556 


Nil 


0.586 


+ 5.4 











0.443 


-23.4 


0.553 j Nil 
























* 




Oak and pine | 






















conv, to oak ! 3.273 


3.107 


- 5.0 


3.300 + 0.8 








-~~ 





3.830 


+ 17.0 


3.746 -14.4 


Note: Pine to oak conversion factor . 


0.833 





for the covering board fastenings, with dire results, and he 
referred to light plywood decking as well as to that used on the 
more solidly constructed vessel. 

He suggested that every commercial vessel should be fitted 
with a doubling over the topstrake, and clear of the caulking 
seam. This strake could be through-bolted as required, for 



easy removal if ever such became necessary. The covering 
board then goes over the topstrake, but fastens only to the 
doubling strake. This protects the topstrake and reduces the 
ever present hazard of dry rot, caused by the leakage of fresh 
water around and under the edge of the covering board, 
thence on to the top edge of the top strake and down into the 



MAIN DUMENS40M. 




Flf. 157. XteomtneHo* of profile and mUHMp ttcthns ofSinyaon't OH 

[170] 



SCANTLINGS DISCUSSION 



TABLE 37 



CriMc contort of timber for' 



Volumes in cu. ft. for 3 



tettng boats as cooqMrttf with Simpson's proposal 

ft, (0.9 17 m.) length midship section 



Boat 
No. 


Timber 


CLASSIFICATION 


Simpson's 
proposal 


New England 
trawlers 
(no regulations) 


Bureau Veritas 
(France) 


Danish 
Regulations 


Swedish 
Regulations 


Newfoundland 
Rubs 


Hanson's 
Scantlings 


As built 


Percentage 
of 
difference 
from 
Simpson's 


As built 


Percentage 
of 
difference 
from 
Simpson's 


As built 


Percentage 
of 
difference 
from 
Simpson's 


As built 


Percentage 
of 
difference 
from 
Simpson's 


As built 


Percentage 
of 
difference 
from 
Simpson's 


Asbultt 


Percentage 
of 
difference 
from 
Simpson's 


6 
68ft. 


Oak 

Pine 


36.10 
8.40 


40.40 
9.40 


+ 11.6 
+ 13.1 


44.37 
11.00 


+ 22.8 
+ 30.8 


50.40 
11.36 


+40.0 

+ 35.4 


47.30 
10.85 


+31.2 
+29.2 


44.15 
9.47 


+22.1 

+ 12.7 


42.40 
8.40 


+ 17.45 
NO 




Oak and pine 
conv. to oak 


43.10 


48.30 


+ 11.9 


53.55 


+24.2 


59.75 


+ 39.5 


56.35 


+30.09 


52.02 


+20.7 


49.40 


+ 14.6 


12 

85ft. 


Oak 

Pine 


50.44 
10.55 


50.18 
10.55 


- 5.1 

Nil 


63.30 
14.60 


+ 25.6 
+ 36.6 


72.40 
12.26 


+43.7 
+ 16.2 


63.65 
14.27 


+26.3 
+ 34.8 


68.6 
11.45 


+ 36.0 
+ 9.0 


61.60 
11.75 


+22.2 
+ 11.4 




Oak and pine 
conv. to oak 


59.24 


58.98 


- 0.4 


75.60 


+ 27.6 


82.60 


+39,5 


75.55 


+27.6 


78.20 


+31.9 


71.40 


+20.6 


20 

115.85ft. 


Oak 

Pine 


90.80 
17.80 


85.45 
17.80 


- 5.9 
Nil 


90.80 

18,75 


Nil 
+ 5.4 











- 


112.0 
13.82 


+23.1 
-23.4 


106.00 

17.83 


+ 16.7 
Nil 




Oak and pine 
conv. to oak 


105.63 


100.28 


- 5.0 


106.48 


+ 0.8 


_ 











123.5 


+ 17.0 


120.85 


+ 14.4 



Note: Pine to oak conversion factor . 



0.833 



topstrake through the innumerable splits caused by the driven 
covering board fastenings. 

This, of course, could happen to the doubling piece, but in 
such an event the repair cost would be ever so much cheaper. 
This method was adopted with marked success in Australia 
during World War II, even with double diagonally built 
vessels, and it is now, of course, on record just how badly, 
most double diagonally planked vessels suffered from dry rot, 
particularly at the junction of the decks and hull planking. It 
is most important that the faying surfaces of both planks 
should be well painted as well as the top edges. 

Some important strength details of select Australian hard- 
woods may be of interest to naval architects. 



Modulus of rupture 

Ib./sq. in. 
(kg./sq. cm.) 
15,000-24,000 
(1,050-1,700) 



Modulus of elasticity 

Ib./sq. in. 

(kg./sq. cm.) 

2,400,000-3,000,000 

(170,000-210,000) 



Crushing strength 

Ib./sq. in. 

(kg./sq. cm.) 

7,500-12,000 

(525-840) 



The first figure in each case is for green timber, whilst the 
second is for timber seasoned to 12 per cent, moisture content. 
Their highly durable hardwoods, such as ironbark, tallow- 
wood, jarrah, etc*, have a useful life in wooden shipbuilding 
of up to 40 years, and in many instances they have commercial 
vessels of over this age still in good order. The rest of their 
shipbuilding timbers would easily give a good life of 25 years. 

COMPARISON OF WOODEN SCANTLING 
REGULATIONS 

MR. D. A, S. GNANADOSS (India): The papers by Simpson and 
Hanson deal with a subject which is fundamental for good 



boatbuilding and they will be much appreciated by all those 
concerned with wooden boat designing and construction. He 
made a comparative study of the scantling regulations for 
wooden boats according to the Bureau Veritas, the Danish, 
the Swedish and the Newfoundland regulations. The main 
object of the study was to determine how these regulations 
compared with Simpson's suggested standard scantlings. 

To facilitate the study the profiles and the midship section 
of the special boats selected by Simpson (boats 6, 12 and 20) 
were drawn up to the given principal dimensions, assuming 
their prismatic coefficient to be 0.575, see fig. 157. 

One metre length (3.28 ft.) of the boat at midship was taken 
as the unit, and the cubic content of timber under the different 
classifications was worked out. The timbers used for the 
calculation are pine for decking and oak for the rest. However, 
for easier comparison, the pine has been converted to oak, 
using a factor of 0.833. The data obtained are given in tables 
36 and 37, and indicate that, 

The small and medium boats are much more heavily 
built than would appear necessary according to Simpson 

The boats built to the Danish regulations are the heaviest 
in the categories analysed 

The Newfoundland rules lay down that where timber 
other than Newfoundland timber is used it may be sided 
and moulded i in. (12.7 mm.) smaller if the construction 
is entirely of hardwood. This reduction does not appear 
sufficient in the larger boats 

It might be possible to evolve unit weights for different 
categories of boats, which may also form a basis for 
estimating the total weight of the hull 



[171] 



PISHING BOATS OF THB WORLD: 2 CONSTRUCTION 

TABU 38 



Principal dimensions Simpson's proposal Bureau Veritas (France) Danish regulations Swedish regulations Newfoundland rules 



LENGTH 



BEAM 



DEPTH 



From fore part of stem 
to the aft of the stern 



Extreme breadth out- 
side the planking 



From fore part of the 
stem to the aft of the 
rudder post 



Widest part of the 
vessel outside the 
frames 



From the top of the From the top of the 
deck at side amidship upper deck beam at 
to the lower edge of sick amidships to the 
the keel rabbet lower edge of the keel 

rabbet 



SCANTLING NUMERAL N~3 



7 



in foot system 
LOAxBxC 



L x B x D 



TS5 
in metric system 



From the aft side of 
the stem to the middle 
of the rudder post 



Extreme breadth out- 
side the frames 



From the top of the 
deck beam at side to 
the inner edge of the 
keel rabbet 



On the summer water- 
line, from the fore side 
of the stem to the 
centre of the rudder 
post or 96 per cent, 
of the length at the 
summer waterline, 
whichever is lower 

Extreme breadth out- 
side the planking 



From the under side 
of the decking at side 
to the lower edge of 
the keel rabbet 



LxBxD Transversal B+2D-R 

where R is the short- 
est distance from the 
intersection of the base 
line plane and the 
vertical plane from the 
extreme beam outside 
planking to the turn of 
the bilge 



From forward part 
of the stem to the aft 
part of the stem 



Extreme breadth at 
deck line inside the 
ceiling 

From the top of the 
beam at the centre- 
line to the top of the 
ceiling on a flat 
bottom 

LxBxDxO.75 
RSS 



in foot system 
2.69 (B+ D) f 
in metric system 



C-NxF 



When the numeral is 
not in the Table 



Longitudinal 
L x Transversal 



Select the lower of the Use the nearest (lower 
numbers or higher) scantling 

numeral 



The possibility of gathering further information to cover 
small boats, to compare the existing scantlings and to 
suggest more judicious and rational use of timbers 

They form a basts for comparing scantling regulations in 
several other countries and to eventually formulate 
uniform regulations 

Simpson's proposals appear a fair basts for determining 
the scantlings and are a fine blend of scientific knowledge 
with practical experience 

It is, however, likely that the suggested standard scantlings 
of Simpson may not be acceptable to the countries whose 
regulations have been taken up for comparison, because of the 
considerably lighter construction indicated which requires 
much departure from the existing practices. These regulations 
are the results of age-old practices and do not rest on a 
scientific basis. The sea conditions, the timbers used, and the 
types of fishing necessitate different methods of construction 
and strengthening. Hence, naturally, they vary from country 
to country, and in many cases even inside the same country. 
Some of the main variations in classifying the vessels for 
scantlings are given in table 38. 

In recent years there has been considerable interest in 
wooden fishing vessels. Many studies have been made on the 
performance, power and resistance and the like, but die actual 
timbers that go into building the boat itself are still mainly 



determined on the basis of past experiences. As yet no method 
has been developed to determine the stresses and strains on 
wooden fishing boats. 

The unique feature of Simpson's proposals is that he has 
evolved an acceptable system of calculating minimum standard 
scantlings for wooden fishing boats of the U.S. East Coast. 
This system is naturally limited in its applicability to other 
countries because of local conditions, but it is reasonable to 
expect that with Simpson's proposals as a basis, suitable 
standards for minimum scantlings could be worked out under 
the various regulations. It is hoped that further research 
work will be done on this important subject, which, as 
Simpson observes, would benefit all concerned with fishing 
boats. 

New type of coustrnctioii 

MR. C. HAMUN (U.S. A.): Simpson was to be congratulated 
on his paper suggesting standard scantlings. For over ten 
years Mr. Hamlin has been designing, almost exclusively, 
yachts of glued-ttrip construction, i.e. the hull is built up of 
square longitudinal strips of wood glued and edge-nailed 
together, with framing largely omitted. Since this new and 
different concept of construction had no previous data upon 
which to base scantlings, it became necessary to create some 
standards of his own. Rg. 158 is a graph he used with success 



[172] 



SCANTLINGS DISCUSSION 



when selecting cedar planking for sailing yachts with displace- 
ments of from i to 10 tons. It would be noted that his longi- 
tudinal number took into account only displacement and 
effective length, defined as (LOA+2xL)/3. This curve has 
served well for a particular type of boat within the range of 
displacements given above. 

Most scantling rules with which he is familiar ignore dis- 
placement. With this omission, it would seem that any attempt 
to match the planking and other structural members to the 
loads they wiU be called upon to sustain will be erroneous. 
For instance, a pilot boat and a sardine carrier may both have 

*% 



29 



1 



tor 


L 

1 

0.8 
0.6 
0.4 

0.2 


Csdar pjontang tncknsss for / 
gbed-strip sotting] yachts / 






/ 








/ 


- 




/ 


/ 


- 




/ 








/ 






05 1.0 \S in. 2.0 



Fig. 158. Hamlin's graph for cedar planking thickness for sailing 
yachts from 0.5 to 16 tons 

the same overall dimensions and hence call for the same 
scantlings under most rules, but the loaded sardine carrier 
will have about twice the displacement of the pilot boat. 

It is his belief that a system of scantling numerals could be 
devised which would apply to any size and type of vessel. He 
suggested that the system takes into account displacement and 
effective length, and possibly includes depth and speed length 
ratio in a minor role. There should be in addition a set of 
coefficients established which would allow for varying strengths 
of materials, arduousness of vessel function, etc. With such a 
universal set of scantling formulae, any boatbuiider anywhere 
could safely select material for any type of boat. 

In fig. 159 are plotted both the actual and recommended 
planking thicknesses for the 22 examples of fishing vessels cited 
in the paper, but using, instead of Simpson's longitudinal 
number, Mr. Hamiin's which was defined as follows : displace- 
ment in tons divided by the effective length, (LOA4 2x L)/3. 



K> 



llO 



o Simpson's proposal 
+ At buBt 


L 


"ft 

10 








! 

t 






a 




4 
t 


. 


d 




+ 4 




o 

ffb ^ 


+ 














16 \ 


JD SO h. 


jiiiMJHJ .INcfcnus 



Fig. 159. Planking thickness from Simpson's examples as built and as 
recommended by Simpson plotted over Ham fin's longitudinal number 



It would be seen that Simpson's recommended spots fall in 
line fairly well, and much better than the actual spots. 

In fig. 160 the Simpson's recommended spots are plotted 
together with several points representing planking thickness 
according to Lloyd's rule for sailing yachts applied to some 
of Simpson's examples, as well as to some very light displace- 
ment sailing yachts. The linear fall of the points would 
indicate the possibility of a longitudinal number such as 
suggested, containing displacement, having universal applica- 
tion for all types of vessels. 

The justification for using displacement divided by length 
as the longitudinal number undoubtedly lies in the fact that it 
expresses the approximate loading per unit of length. 



^ 


Lloyd's rUe I 


o 




o Svnpson'i proposal 


00 


so 





_ _ _ 




c 

I 




J~ 




o 




! zo 


___i 


I 


ir 




# 


" 


i 


i 




/ 




ft 




o 


10 






i 


1 




o 




~i 
i 





* 


j 


L 16 20 bi SO 


, .-g^ ._^. #.;_.->* *> 



Fig. 160. Simpson's recommended plank thickness for sailing yacht* 
compared with Uoyas" rules 



[173] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



amH 



60 



40 




Actual ships 

A Japanese gov. rule (HinoW* Cypress) 

A (Sugi Cedar) 

o Pishing, boot soc, rule (HinoW) 



I 



5 6 7 N 

Fig. 16] . Simpson's recommendations for planking compared with 
Japanese standards 

Although considerable data exist regarding the stresses 
imposed upon a vessel at sea, there are relatively few regarding 
the strength of vessels' hulls; the scatter of Simpson's "as 
built" points demonstrates better than anything else the lack 
of science in this area. It seemed to him that an experimental 
model investigation of ship strengths could be carried out 
profitably and inexpensively. 

He proposed that a simplified standard parallel mid-section 
be adopted as the basic test section. It might be semicircular 




30 



fig. J62* Japanese frame-spacing, indicating that these are larger for 
small boat* and shorter far targe toot* than thoM proposed by 
Simpson 



in section, with a length equal to twice the beam, thus 
approaching the maximum unstiffened length of hull probably 
encountered in practice. For simplicity, there would prefer- 
ably be no deck crown. All construction details would be 
exact scale representations of the full-size vessels. For varia- 
tions of beam/depth ratio the sections would become semi- 
elliptical. Being prisms, the "hull" could be built in long 
lengths inexpensively, allowing uniform testing of several 
different factors. 

Forces encountered by a ship's hull could be reproduced 
approximately by cantilevcring the test section out from a 
rigid base and acting on the free end with various machines. 



50 



800 1- 



CLubrnJ 



Acluot ahipt 

Japanese gov. rub (KtyoM 



o FfcNng boa, 



40 



6600' 



20 



200 



;o 




NxF 



Fig. 163. Simpson's recommended figures for section moduli of 
frames falls between the two Japanese standards 



The major effects to be exerted by the machines would be 
hogging, sagging, a combination of the two in flexure, and 
torsion. 

Standardization of test procedures and measurements, etc. 
would be necessary to insure the fullest usefulness of such a 
programme. The basic hull section should be tested in various 
constructions, such as conventional wood with moulded and 
bent frames, fibregkss, glued-strip, moulded plywood, alu- 
minium, steel, etc. The construction method, materials and 
scantlings should be carefully defined, preferably by formula, 
to permit reproductibility. The principle of the Standard 
Series should be adhered to hi all variations from the basic 
tests. The results should undoubtedly be given in terms of 
yield strength. Perhaps an experimental engineer could help 
avoid the pitfalls of scale effect in materials testing* 



H74J 



SCANTLINGS DISCUSSION 



Mr. Hamlin urged that as much attention be given to the 
small fishing vessels as to the large. He rather regretted that 
Simpson did not extend his studies down into the lower limit 
of size, i.e. perhaps to 20 ft. (6 m.). In making damage surveys 
for insurance companies, his experience with fishing vessels 
under about 50 ft. (15 m.) LOA has been that usually the cost 
of repairing damage is much higher than the severity of the 
accident warrants. This invariably results from inconsistent 
and unbalanced scantlings. The establishment of universal 
scantling standards would benefit insurance companies by 
reducing the settlement load, benefit the fisherman by reducing 
his insurance cost and increasing confidence in his boat and 
benefit the builder by materially advancing the art. 



40 



600|_ 

cuin. 
cucm 



30 



400 



20 



5200 



(0 



x Actual ships ' I9/ 

A Japanese QOV rule (KyoW~ Zafoova) *' 
A (MotsuwPine) 

o Fishing boat soc. rule (Keyaki) //*20 
. (Matsu) 




25ft. 



8 max. 



7m. 



Fig, 164. Simpson's section moduli of deck beams compared with 
the two Japanese standards 

Standards in Japan 

PROFESSOR A. TAKAGI (Japan): In Japan there are about 
1,000,000 gross tons of wooden fishing boats. Simpson's 
paper, giving new standards of scantlings and fastenings for 
wooden boats, is very useful. Japan uses two standards for 
wooden boat construction, namely the Government's Wooden 
Boat Construction Rules, and that to be issued by the Fishing 
Boat Association of Japan, which is still in draft form. Some 
comparisons have been made between these two standards 
and those put forward by Simpson. See fig. 161 to 166 and 
table 39. The results are as follows: 

Member Simpson's Numeral N Comparison 
Planking 4 to 5 Japanese is thicker 

Over 6 Japanese is thinner 

Frame space Below 6 Japanese is larger 

Over 6 Japanese is smaller 

Section modulus of frame: Simpson's figure falls between 
two Japanese Government standards for wooden 
fishing boats and general wooden boats. 



15 



20C 



A Jopmw ov rule <K*yc*i~; 
A (Motou ~ Ptne) 

o FfcNng boot toe. rule (KsyoU) 




ft 



25 



30 



35 m. 



Fig. 165. Simpson's proposals for keels compared 
smaller required by Japanese rules 



with the much 



Keel based on L: Simpson's suggestion is much larger 
than the Japanese standards but the same if the keelson 
is included. 
He would be glad to have some points clarified : 

The minimum thickness of the planking when N is very 
small, especially regarding the minimum necessary 
thickness of planks for caulking and fastening with nails 

Generally speaking, the keelson is larger than the keel in 
Western wooden boats, but in Japan the keelson is always 
smaller than the keel, and so it is in Simpson's paper. Is 
there any reason for the Western countries* practice? 



* Actual ships 

Japanese gov. rule (Keyaki 
A (Molsu-fW 

o Fishing boot- soc. rule (Keyaki) / 
(Matsu)/ * 





22* 



CO ft 



Fig. 166. Simpson's proposals for keels and keelsons being similar to 
the Japanese rules 



1175] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



TABLE 39 





Ship No. 




3 


4 


6 


12 


| 




LOA 
L.92LQ/ 
B . 
B-2t 
D . 


i 


ft. in. m. 
55 10 17.02 
15.66 
15 4.57 
4.48 
8 2.44 


ft. in. m. 
62 18.9 

16 idT 5.13 
8 8 2.64 


ft. in. m. 
68 20.75 
19.09 
17 5.18 
5.05 
8 10 2.69 


ft. in. m. 
85 25.9 
23.83 
19 7 5.96 
5.85 
9 7 2.92 


ft. in. m. 
97 7 29.44 
27.08 
21 7 6.58 
6.44 
11 9 3.58 




N . 
F . 

NxF 
B/2+D 




4.06 
135 
548 
4.68 


4.49 
163 


4.68 
167 
783 
5.22 


5.51 
212.5 
1,170 
5.85 


6.26 
277.9 
1,740 
6.80 


Fig. 161 


Plank thickness 


A 
S 

T /Hinoki 
J \Sugi 
P/ Hinoki 


in. cm. 
4.5 


in. cm. 

"~ 


in. cm. 

5 
6 
5 
5.5 


in. cm. 

6 
5.5 
6 


in. cm. 

2f 6.7 

6 
7 
6 
6.5 


Fig. 162 


Frame spacing 


A 
S 
J 
F 


in. cm. 
10 

~~35.7 
41 


in. cm. 

16 _ 




in. cm. 
16 
15 
39.1 
43 


in. cm. 
18 
18 
43.8 
46 


in. cm. 
20 

-47, i 

50 1 


Fig. 163 


Section modulus of 
frames (bilge part) 


A 

S 
J/Keyaki 
\Matsu 
F/Keyaki 


cu. in./ft. 
8.5 
8.2 
6.17 
8.45 
10.5 


cu. in./ft. 


cu. in./ft. 
12.62 
11.50 
8.95 
11.73 
13.3 


cu. in./ft. 
20.0 
17.5 
10.5 
15.1 
18.8 


cu. in./ft. 
24.9 
26.1 
19.5 
23.8 
28.6 



\Matsu 



14.0 



18.0 



25.5 



37.2 



Fig. 164 



cu. in./ft. 
8.8 



cu. in./ft. 



cu. in./ft. 
13.5 



cu. in./ft. 
21.1 



cu. in. 
23.3 



/ft. 





OTCK acorns luramory; 


J/Keyaki 
\Matsu 
F/Keyaki 
\Matsu 


J 6.42 
8.25 
13.7 

1 1M 





iy.<* 4L.& 
9.50 10.5 
11.75 14.1 
18.8 , 22.5 
20.5 24.3 


11.9 
15.7 ! 
24.1 

27.9 


Fig. 165 


Sectional area of keel 


* 

S 

i f Keyaki 
J \Matsu 
F > Keyaki 
F \Matsu 


sq. in. 
84 
85 
45 

s 

58 


sq. in. 
162 
98 


sq. in. ! sq. in. 
162 180 
113 162 
53 58 
62 82 
58 97 
82 113 


sq. in. 
200 
213 
86 
101 
130 
168 


Fig. 166 


Sectional area of keelson 


A 
S 

./Keyaki 
J \Matsu 
F r Keyaki 
r 1 Matau 


sq. in. 

43 
107 
128 
106 
120 


sq. in. 
80 
49 

i 


sq. in. ' sq. in. 
80 80 
57 I 81 
125 ! 155. 
148 195 
120 186 
157 ' 222 


sq. in. 
120 
111 
208 
245 
252 
317 



J 



A 
S 



Actual ship data 
Simpson's paper 



J 
F 



Japanese Government's Wooden Ship Construct ion" Rule (1958) 

wooden Fishing Boat Construction Rule (1958) of the Fishing Boat Association of Japan 



How was the relationship between the section modulus per 
foot length of the ship and the maximum beam obtained ? 

Japan has Steel Fishing Boat Rules, and standards for 
wooden fishing boats arc being drawn up. Are there any 
similar standards for fishing boats in other countries ? 

MR. J. TYRRELL (Ireland): Simpson's proposals should be of 

[176 



considerable value for new vessels of the types and in the 
districts he has investigated. 

Equally satisfactory vessels of quite different scantlings and 
construction methods have been developed independently in 
other parts of the world, and to these research similar to that 
carried out by Simpson might profitably be applied, so that 
different standard specifications could be arrived at. He felt 

J 



SCANTLINGS DISCUSSION 



TABLE 39 (continued} 
Comparison of Simpson's proposal with the 





Ship No. 




18 


19 


20 


21 


22 








ft in. m. 


ft. in. m. 


ft. in, m. 


ft. in. m. 


ft. in. m. 




LOA 




110 33.53 


112 34.14 


115 10 35.3 


123 6 37.64 


140 42.67 




L~.92LO 


A 


30.85 





32.48 









B . 




23 7.01 


23 9 7.24 


23 9 7.25 


23 9 7.24 


27 3~~ 8.31 




Bm-2t 




6.86 


7.09 


7.14 


_ 






D . 




12 6 3.81 


12 3 3.73 


14 3 4.35 


12 8 3.86 


12 7~* 3.84 




N . 




6.75 


6.90 


7.26 


7.17 


7.86 




F . 




306 


325 


363 


336 


399 




NxF 




2,063 


2,240 


2,635 


2,405 


3,135 




B/2+D 




7.24 


7.28 


7.92 














in. cm. 


in. cm. 


in. cm. 


in. cm. 


in. cm. 


Fig. 161 


Plank thickness 


A 








3 











S 








3J 












i/ Hinoki 


- 










-_ 






\Sugi 


Jr 











__ 






P/ Hinoki 





















F \Sugi 























in. cm. 


in. cm. 


in. cm. 


in. cm. 


in. cm. 


Fig. 162 


Frame spacing 


A 


21 


24 


20 


21 


24 






S 








23 


__ 


_ 






J 


50,9 
















F 


51 


52 

















cu. in./ft. 


cu. in./ft. 


cu. in./ft. 


cu. in./ft. 


cu. in./ft. 


Fig. 163 


Section modulus of 


A | 








28.1 


38.9 


47.3 




frames (bilge part) 


S 








39.3 


36.1 


47;0 






,/Keyaki 
J \Matsu 


22.1 
29.1 




z 


z 









P/Keyaki 

r \Matsu 





34^ 
46.0 

















cu. in./ft. 


cu. in./ft. 


cu. in./ft. 


cu. in./ft. 


cu. in./ft. 


Fig. 164 


Section modulus of 


A 








32.1 


- 







deck beams (ordinary) 


S 








34.3 












,/Keyaki 
J \Matsu 


14.5 

18.7 


z 








- 






P/Kcyaki 
F \Matsu 


"- 


33.1 

37.7 

















sq. in. 


sq. in. 


sq. in. 


sq. in. 


sq. in. 


Fig. 165 


Sectional area of keel 


A 








288 


288 


. 






S 








314 


288 


_ 






,/Keyaki 
J \Matsu 


97 
113 





z 


z 









P/Keyaki 
F \Matsu 





- 


236 
286 














sq. in. 


sq. in. 


sq. in. 


sq. in. 


sq. in. 


Fig. 166 


Sectional area of keelson 


A 








144 


144 


168 






S 








157 


144 


196 






j/Keyaki 
J \Matsu 


237 
277 


- 








- 






F /Keyaki 
F \Matsu 








405 
495 









A -Actual ship data 
S ** Simpson's paper 



J Japanese Government's Wooden Ship Construction Rule (1958) 

F -Wooden Fishing Boat Construction Rule (1958) of the Fishing Boat Association of Japan 



that such investigations should be sponsored by the Fishery 
Departments of the countries concerned, since it would be 
unreasonable to expect naval architects or builders to conduct 
so much research at their own cost. 

His firm's standard multi-purpose vessel, 56x17x8 ft. 
(17. 1 x 9.2 x 24 m.), with 44 tons displacement when ready for 
sea* compared for framing and planking as follows: 



Frame spacing 
Plank thickness 
Frame section at bilge 



Simpson Tyrrell 

13 in. (330 mm,) 16 in. (406 nun.) 

If in. (41 mm.) IJin. (44.5mm.) 

2.25x5.12 in. 3.25x5.5 in. 

(57 x 130 mm.) (82.5 x 140mm.) 



It is surprising to find larch given such a low classification in 



[177] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



tabfc29. Thia is the Irih standard ntatcrial for planking, and 
is a most reliable timber, very resistant to rot, and of excellent 
steam bending properties. There must be a considerable 
difference in the U.S. and Irish varieties. 

Galvanised mild steel plank spikes are first-class in lasting 
and holding power. He thought those shown in Simpson's 
fig. 1 53 were quite unsuitable for planking or in other positions 
of$tras. 

Their standard spike had a rose head, and taking the 5 in* 
(12.5cm.)asanexampk,hada9ectionof J x iin.(9.5 x 6.35mm.) 
under head, tapering to & x J in. (7.8 x 3.2 mm.) at the point. 
These were driven with the point at right angles to the grain 
of the frame, prebored by & in. (7.8 mm.) drill through the 
plank and about i in. (19 mm.) into the frame. 

Lag screws were not reliable in any position subject to stress. 

In fig. 146 (mid-section) the topside planking was shown of a 
standard thickness. The Irish current practice in the vessel 
referred to above, was to fit three 7 x 2$ in. (178 x 63 mm.) top 
wales. It was noted that through fastenings are fitted before 
planking. They consider this in Ireland as bad practice and fit 
all such bolts through outer planking. 

Bent frames would not at all do in his area. In shallow 
harbour entrances the boats were subject to heavy knocking 
on the bar when entering port. He strongly advocated well- 
prepared plank seams, tight inside, and judicious application 
of caulking. Lock scarves were made in keels and rails in his 
yard. He felt the best fastenings to be bolt and nut, although 
drift bolts could be satisfactory. 



Scandinavian practices 

MR. H. K. ZIMMBR (Norway) : Standard scantlings for wooden 
fishing vessels are not a new thing. Apart from the classifica- 
tion societies* Lloyds Register of Shipping "Rules for Wood 
and Composite Vessels 1929*' and Del Norske Veritas' 
(Norwegian Veritas) : "Regler for bygging og klassifikasjon av 
treskip 1955" (in Norwegian only), there are the Danish: 
"Bekendtgorelse angaende Forskrifter om Bygning og 
Ombygning m.v. af Fiskefartoycr 1947" and the Swedish 
"Regler fdr byggandet av fiskefartyg av tra 1952". 

These rules are based on local practices like the proposed 
standard, but the discrepancy of practice may be consider* 
able. For instance: the Swedish practice of making keelson 
and floors of a reinforced concrete construction. 

The Danish rules, which are the simplest, are based on a 
Numeral: (LxBxD) and cover the range of 33 to 84 ft. 
(10 to 25.5 m.). The Swedish rules are based on a transverse 
Numeral : (B -h 2D R) and a longitudinal Numeral, 
UB+2D-R), R being the distance from the bilge to the 
lower corner of square B x D. 

The different standards seem to give similar results although 
there are some points worth taking note of. 

Scantlings of dck beams are based on B alone in Scan- 
dinavian rates, and the dimensions are heavier and the spacing 
correspondingly larger. These rules give adequate strength 
and render a cheap hull, 

The tad is the backbone of the hull, and one of the most 
apparent and common defects ef wooden hutts is the hogging 
of the ked and often the complete hull. The siding of 
Simpson's proposed scantlings is decidedly smaller than 
Scandinavian practice, fits experience catted for increased 
strw^thinthektelandthekedson(hog). It is most essential 
that longitudinal members like the keel, keelsons, bilge 
stringers, clamps, lodgers (shelf) and waterways are jotaed by 



scarphs to enable them to take up longitudinal strain (tension) 
efficiently. 

The butts of the planking should be well staggered and butts 
of deck planking must be kept well away from hatch corners 
to avoid leakage there and also to increase longitudinal 
strength. 

Looking at the keel construction alone, i.e. the keel with 
garboards and keelsons, the main strain will be compression 
in the keel and garboard, and tension of the keelsons, scarphs 
are therefore most essential in the keelsons. He experienced 
good results when strengthening existing, weak vessels by 
fitting a channel steel section upside down over the centre 
keelson with secure fastenings at the ends. The Swedish type 
reinforced concrete keelson is another solution that may be of 
advantage in small seagoing vessels that call for extra weight 
stability. 

Hanging knees and riders of steel were not mentioned in the 
proposal. The knees may not be required due to the suggested 
small beam spacing but the riders certainly have a mission to 
avoid hogging. Ceilings of double diagonal construction 
between the bilge stringers and clamps would also help to 
resist hogging. 

Simpson remarked in his paper that the basic vessels would 
have ice protection, Mr. Zimmer presumed that the scantlings 
were not intended for navigation in ice. Scantlings for vessels 
like sealers might be considered separately. 

One of the main drawbacks of wooden vessels is their 
tendency to rot. Copper naphthanates etc. might be useful as 
preventive measures, but there is nothing like salting of the 
space between the ceiling and the skin planking from the bilges 
to the clamps, combined with adequate ventilation of the space 
above. It was perhaps this tendency to rot which helped the 
advent of steel hulls. Today there are hardly any wooden 
hulls longer than 80 ft. (24 m.) being built in Norway. The 
upper range of the proposed scantlings seems to be outside 
future trends, whereas the lower range is not covered by the 
proposed standards. 

He recommended that FAO should continue the research 
done by Simpson with the aim to produce more simplified 
standards that could be of international use. Cooperation 
with the leading classification societies in this work might be 
an advantage. 

MR. P. ZIENER (Norway): Simpson's suggested scantlings are 
for a specific area. The question arises whether they could be 
used for similar boats in other regions in the form they now 
appear. In his opinion this would not be recommendable, 
because operational conditions, building woods and con- 
venient construction modifications would in most cases 
demand scantlings and fastenings quite different from those 
arrived at by the proposed numerals. 

For instance, the resulting dimensions are far too heavy for 
most fishing boats operating in tropical waters, not consider- 
ing the extensive use of hardwood in those regions which 
would require further substantial reductions. 

For near-Aictic waters where wooden fishing boats are 
seasonally employed in seal catching and Arctic hunting, the 
scantlings would result in hulls too weak even if prescribed ice 
reinforcements were added. 

A standardization as proposed is undoubtedly valuable if 
strictly limited to defined areas, and might well include 
machinery and certain equipment. Operational demands, 
materials aadmttstKiictiion tecta^ 

not die world that the suggested principle of standardization 
hardly could be universal. 



[178} 



SCANTLINGS DISCUSSION 



MR. E. MCGRUER (U.K.) : The numeral system is already used 
by the Classification Societies and recent yacht scantling rules 
is based on it. He hoped that people versed in construction 
method* would join a boatbuilders' forum and develop 
Simpson's proposals. 

In Scotland frames have greater moulding at the turn of the 
bilge, and he thought a better section could be had by not 
having a mass of material in the inner ceiling so near to the 
neutral axis as indicated in fig. 146. 

Referring to the fastenings of a wooden ship, he thought 
that those who encouraged the use of nature's bounty for 
boats were entitled to say that a steel ship was no better than 
its welding, and a fibre glass hull no better than the unskilled 
labour that is claimed could build it. Nor was the laminated 
boat better than the glue. 

As the inventor of an early laminated hollow spar, he felt 
entitled to glue parts of a boat, combined with early ship's 
carpentry methods, proper riveting and dovetails and inter- 
lockings, so that in the event of a glue-line failure, the structure 
would not fall apart. 

He thought the Belgian fluted, square-section nail was 
excellent. It had a greater and more effective bearing surface, 
was easy to drive and was as light as a round fastening, 
because each side of the square section was concave. As a 
general principle, boat nails should be square. He referred 
also to the ringed nickel alloy nail for use as a non-corrodible 
spike. 

In the Museum at Lake Nemi, Italy, can be seen wrought 
square nails of various lengths up to 24 in. (610 mm.), all 
nicely tapered from about i to i in. (20 to 6 mm.) and with 
such neat heads and finely worked points for plying-over. 
These long nails could not be driven. Rather were they lacings 
tying one hull member to another. The Romans would find it 
easier to work a square tapered nail than a round one and 
this is perhaps the primary reason for the square section. But 
there can be no doubt the tapering square would fill the drilled 
pilot hole better where water might have ingress. 

Preference for the square nail is based on its greater resis- 
tance to shearing stresses between the members fastened, and 
not on axial pull 

The constructional design of a good draughtsman should 
use the old shipbuilder's term "room and space" to represent 
the distance between the molded edge or face of the frames; 
siding is in the space and the room is the space left between 
the frames. Sidings vary with the different builders. 

He should like to help in the question of how a boat design 
specification should be presented to the boatbuilder, the 
owner and the Classification Society. 

He felt the methods of sawing the tree for scantlings, par- 
ticularly for planking, should be reconsidered. He suggested 
the boatbuilders should revert to the early sawer's method of 
quartering the tree before culling the planks. This quartered 
wood had much less shrinkage than the tangential wood, 
which was common now. It was necessary to make quite 
certain that the materials used were properly sawn. 

He suggested slightly lower rise of floor, but advocated the 
use of a hollow garboard to add considerably to the strength 
of the hull. Regarding the keelson, he suggested this with 
intercostals between the framesshould be treated as a part 
of the keel itself to get a good section modulus. 



M*. H. R. BAftDAftftON (Iceland): He discussed Hanson's and 
Simpson's papers together. In Iceland they have had rules 



for wooden vessel construction for several years. They were 
based on the experience of the hardest use any fishing vessel 
could suffer : North Atlantic service during the winter season. 

They were always putting trigger and bigger main engines 
into these ships. A 71 ft. (21.6 m.) long vessel (about 90 GT) 
would have a main engine of about 400 h.p. Normally, small 
fishing harbours in Iceland were open to the sea; often five or 
more vessels were tied up side by side, bumping against each 
other and the harbour walls during rough weather. For some 
harbours it was even necessary to have a U-shaped steel piece 
on the bottom of the keel and up the stem to ride over the 
rocky bottom when entering port at low tide. Almost all 
wooden ships over 46 ft. (14 m.) in length (about 20 GT) 
were built of oak with sawn frames. Bent frames were only 
used for the very small ships. Keels, keelsons, frames, stems, 
stern posts, planking, deck beams and other main strength 
members were of oak. Decks, bulkheads were of fir or pine 
and ceilings in fish hold of oak or fir. 

Owing to the Icelandic rules for the construction of fishing 
vessels, boatbuilders and boatyards in other countries build- 
ing for Iceland never had to do any guesswork, and no builder 
could tell the owner that his ships were stronger than those 
of another builder. He was well aware of the fact that they 
used more timber (oak) and possibly more galvanized bolts, 
than would be used for similar size vessels in other countries. 
He believed that a strong and seaworthy ship was required 
above all, even if it were somewhat heavy. 

The Icelandic rules were based on tables for scantlings, the 
main scantling numerals being: 

the athwart ship numeral : B -f D 4- G/2 

the longitudinal numeral : L(B + D + G/2) 

the breadth numeral: B 

L was the length of the ship between forward end of stem to 
after the end of stem, measured on deck, B the greatest 
moulded breadth, D the depth amidships from top of keel to 
lower edge of deck at side and G the girth amidships. 

In order to compare the amount of timber needed for a 
ship according to the Icelandic rules, with the ships mentioned 
in Simpson's paper and Gnanadoss* comments, he had 
calculated the oak and fir needed in cubic metres of timber for 
one metre length amidships, for the usual Icelandic type of 
vessels and according to their rules. This cubic figure was 
based only on the section in the fish hold. The material for 
stem, stern frame, engine seatings etc., was not included. For 
a 55 GT vessel with the dimensions of 77xl7.7xS.5 ft. 
(23.4 x 5.4 x 2.6 m.) they needed 70.5 cu. ft. oak and 20 cu. ft, fir 
for 3 ft. length midships (2.183 cu. m. oak and .616 cu. m. fir 
for one metre). For a 75 GT vessel 80 x 1 8.2 x 9.2 ft. (24.34 x 
5.55x2.8 m.) they needed 81 cu. ft. oak and 23.3 cu. ft. fir 
(2.506 cu. m. of oak and .721 cu. m. fir). 

Icelandic ships, down to about 50 GT are now also built of 
steel, mainly of all-welded construction, owing to the increas- 
ing problem of rot in wooden fishing vessels. About half the 
new Icelandic vessels below 100 GT are still built of oak. 
Good oak has proved to be the best wood for the building of 
strong vessels, but it Was difficult to find a good preservative, 
as the known coatings did not penetrate the wood far enough 
without expensive drying and pressure treatment. 

It may be of interest to know that they had vary good 
experience in Iceland with all-welded steel engine settings in 
wooden ships, bolted with galvanized bolts through the frames 
and plankings. When auxiliaries were connected to Che mam 
engines, the seatings for these and the main engines were the 
same. These steel engine beds were important additions to the 
strength of the afterbody of the vessel, strength which was 



( 179 ] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



very much needed with high horsepower engines built into 
thete comparatively small ships. 



Ma. W. P. MILLER (U.K.) : He felt that uniform specifications 
would not suit all types of boats in the world. The boat- 
builders should evolve a few standard specifications which 
would suit various types of boats under different conditions. 
Timbers vary from country to country, and for that reason 
uniform specifications will not satisfy every boat. 

Twelve years ago the Scottish Fishing Boat Builders* 
Association (SFBBA) issued a catalogue with specifications 
for several types of wooden fishing boats in the 30 to 80 ft. 
(10 to 24 m.) length range. Two years ago the White Fish 
Authority in Scotland took up these specifications and asked 
for something better more concise and with wider coverage. 
The White Fish Authority and the SFBBA have been working 
on this together for two years now. 

In 1958 he had occasion to visit fishing boat yards in many 
parts of the world and he took the opportunity to show them 
the catalogue of the Association. People everywhere expressed 
considerable interest in the publication and felt the necessity 
for issuing similar publications in their own areas. The 
customer gets normally very little information from the boat- 
builder on the details and specifications of boats. He felt it 
was necessary that publications, giving all details of boats, 
should be made available to prospective boat owners so that 
they could make their best choice. 

Before commencing the drawing up of new specifications, 
the White Fish Authority conducted some preliminary 
investigations. Information was obtained from the authorities 
concerned with the Danish regulations and the Icelandic 
regulations. Bureau Veritas, however, could not furnish the 
English version of their regulations. He suggested that all 
standard specifications should be published by FAO. 

He felt one of the most vital points in boatbuilding was 
proper preservation of the timber. His idea was that timber 
should be permitted to be preserved by the natural element of 
the air and that all dead air spaces should be avoided. Pre- 
serving timber by air should be one of the major points of 
study by naval architects. 

It was his opinion that the practice of fitting a keelson was a 
relic from the days of sailing boat construction, but boat- 
builders were now faced with the problem of accommodating 
huge, heavy engines. It was necessary to distribute the weight 
and the vibration of the engine to the whole structure of the 
boat. 

i in UK. 

MIL A. SUTHERLAND (U.K.) had read with very great 
interest Simpson's paper. The Scottish Committee of the U.K. 
While Fish Authority had been working on a Minimum 
Standard Specification for Wooden Fishing Vessels since 1956 
and the papers are now in preparation for printing. 

It would be as well to describe briefly part of the functions 
of the White Fish Authority in order to explain the Authority's 
standing in the matter. 

By Section 4 (1) (g) of the Sea Fish Industry Act, 1951, the 
Authority was empowered to give financial assistance by way 
of loan to meet capital expenditure incurred in providing, 
acquiring, reconditioning or improving fishing vessels or their 
gear. The White Fish Industry (Grants for Fishing Veueis 
and Engines) Scheme, 1953 came into operation under the 
White Fish and Herring Industries Act, 1953, whereby the 



Authority were empowered to grant money towards the cost 
of fishing vessels not exceeding 140 ft. (42.7 m.) in length. Very 
broadly the assistance for a new vessel now tak the form of a 
grant of 25 per cent, of the total cost (with a grant ceiling of 
30,000 or $84,000) and a loan under favourable rates of 
interest of up to 60 per cent, of the total cost. In the case of 
wooden inshore fishing vessels the grant to working owners is 
30 per cent, of the cost (grant ceiling 5,000 or $14,000) 
with a loan of 55 per cent. 

As a condition of such assistance the vessels and engines 
have to be constructed and equipped to the satisfaction of the 
Authority. This involves the submission of plans, specifica* 



TABLE 40 

Comparison of Scantlings 

(as recommended by Simpson and for Scotland) 
Simpson's vessel No. 6 



Proposed by Dwight S. Simpson 


Proposed for Scotland 
} 


Plank thickness U in. 


Uin. 


Frame spacing 15 in. 
Frame sided 2 j in. 


15 in. 
4 in. (clamps 3 in.) 


Frame moulded head 4J in. 


51 in. 


Frame moulded bilge 5| in. 


7 in. 


Frame moulded keel 7} in. 


11 in. 


Beam space 15 in. 


17 in. 


Beam moulded 5} in. Main 
Beam sided 4 in. beams 


/7in. 
\6 in., ordinary beams 




5 in. x 4 in. 


Keel 71x15 in. 


81x12 in., plus hog 




6 in. sided 


Keel shoe 2\ in. 


6x} in. steel convex 




bar 


Keelson 71x7* in. 


6x8 in. 


Sternpost and log 1 3 in. 


81 in. (swelled in way 




of tube so that 25 per 




cent, of thickness 




remains on each side) 


Garboard strake 2 if in. 


11 in. 


Clamps 2} x 131 in. 


10x3 in. (beam 




(stringer) 


Shelf 3| x 81 in. 


6x31 in. (beam shelf) 


Lock strake 21x4* in. 
Lodger 


4 in., beam knees 


Bilge ceiling 2| x 32 in. 


8 x 3 in. bilge stringer 


Decking 2 in. 


2 in. 


Bulkhead sheathing I in. 


11 in. 


Bulkhead stiffeners 2} x 41 in. 


3x4in. 




2 at 3 in. bilge strake 




4 at 3 in. rubbing strake 



tions and tenders from any applicant desiring a new fishing 
vessel and the subsequent examination of the vessel whilst in 
process of building and during the handing over trial trip. 

The Authority insists that steel trawlers should be built to 
Lloyds classification. However, there were no recognized 
rules for classification of wooden fishing vessels and practices 
varied from port to port in Scotland. The rise in costs of 
vessels had been causing some concern and it was felt that by 
standardizing the ncantHngt of fishing vessels and their 
equipment boat builders would then submit tenders on similar 
basis and fishermen would be certain of a well-found boat. 
There was accordingly set up a working party consisting of 
three wril known Scottish boat builders, a technical consultant, 
a representative from Lloyds holding a watching brief and the 
Senior Technical Officer of the White Fish Authority, who 
eventually produced the Standard Specifications referred to 



[180] 



SCANTLINGS DISCUSSION 



which have now been approved as a condition of Grant and 
Loan assistance for Scottish vessels. 

Hie majority of the scantlings wore fixed by means of 
previous submission and methods of fastening were carefully 
studied before the final choice was made. Sizes of rudder stock, 
chains and rods were estimated by using Lloyds Rules for 
rudders. 

Special attention was given to the methods of ventilation 
to try and eliminate decay in timbers and to cut down the 
danger of fire in the engine room. The lining of fishrooms 
except in special circumstances is forbidden as experience 
has shown that the entrapping of air leads to rapid decay of 
the structural members of the vessel. 



TABLE 41 



Comparison of i 

(as recommended by Simpson ancffor Scotland) 



Simeon's vessel No. 12 



Proposed by Dwight S. Simpson 



Proposed for Scotland 



Plank thickness 


2* in. 


21 in. 


Frame spacing 
Frame sided 


U 

31 


tin. 
in. 


20 in. 
5 in. double (10 in.) 


Frame moulded head 4; 


in. 


6 in. 


Frame moulded bilge 


6; 


in. 


8 in. 


Frame moulded keel 


8; 


in. 


12 in. 


Beam space 


U 


: in. 


20 in. 


Beam moulded 


6 


in. Main 


/8in. 


Beam sided 


4 


in. beams 


\8 in., ordinary beams 








8x6 in. 


Keel 


9x18 in. 


10x14 in., plus hog 








8 in. sided 


Keel shoe 


3 


in. 


6 x f in. steel bar 


Keelson 


9x9 in. 


10x11 in. 


Side keelsons 






7 in. sided (engine seats 








extended full length) 


Sternpost and log 


16} in. 


10 in. (swelled in way 








of tube so that 25 per 








cent, of thickness 








remains on each side) 


Oarboard strake 


3| in. 


2* in. 


Clamps 


2Jxl9iin. 


20x4 in. plus 10x3 in. 








(beam stringer) 


Shelf 


44x10 in. 


14x4 in. (beam shelf) 


Lock strake 
Lodger 


2}x5in. 


} f 
41 in bean* lnv** 
1 ^^ 




Bilge ceiling 


2} x 38 in. 


32 x 3 in. bilge stringer 


Decking 


2 


tin. 


21 in. 


Bulkhead sheathing 


1; 


tin. 


i in. steel 


Bulkhead stiffencrs 


2 


[x4f in. 


2J x 2i x iin.anglciron 



TABU 42 



OriMe 



for I 



For 3 ft. (0.917 m.) length 









Scottish 


Boat 




Sittwson's 


Regulations 


No. 


Timber 


proposal 


As built 


Percentage 

of difference 










from 










Simpson's 


6 


Oak 


36.10 


39.0 


+ 8.0 


68ft. 












Pine 


8.40 


8.4 


Nil 




Oak and pine 










conv. to oak 


43.10 


46.0 


+ 2.3 


12 


Oak 


50.44 


77.0 


+ 52.6 


85ft. 












Pine 


10.55 


11.5 


+ 9.0 




Oak and pine 










conv. to oak 


59.24 


86.57 


+46.1 


20 


Oak 


90.80 


__ 


^ _ 


115.85ft. 












Pine 


17.80 










Oak and pine 










conv. to oak 


105.63 









Note: Pine to oak conversion factor . . . 0.833 

the ability of vessels built in this way for generations gave the 
basis from which to work. 

Using the Scottish method of calculating scantling sizes 
Mr. Sutherland had drawn up tables 40 and 41 of comparison 
for vessels No. 6 and 12 in table 30 of Simpson's paper. 
The Scottish Scantling Numeral at present does not go 
beyond a 90 ft. (27.4 m.) overall vessel. Also attached is a 
sectional view of the method of construction, fig. 167, used in 
Scotland and compared with that as shown in Simpson's 
fig. 146. 

Using these comparisons he estimated the amount of wood 
used in a 3 ft. length of each vessel amidships and the difference 
in cubic content is as shown in table 42 which is an extension 
of table 37 by Gnanadoss. 



Regulations for life-saving and fire fighting equipment are 
insisted on by the Ministry of Transport and a close liaison 
is maintained with that body. 

There are of course differences in methods of construction 
and in general the Scottish type of wooden fishing vessel is 
broader in the beam and deeper for similar lengths than those 
described by Simpson. 

The Scottish tables are based on a Scantling Numeral 
obtained by multiplying LxBxD where L is the length 
overall, B the greatest breadth of the vessel and D the distance 
from the underside of the keel to the top deck beam at side in 
the middle of the rule length. 

These standards have been adopted from tried practice 
cutting out certain methods of building and fastening which 
had been found wanting, and substituting these wi A approved 
methods. It will be argued that this is not die correct way but 




Fig. 167. Typical Scottish wooden ship construction 



PISHING BOATS OF THfc WOULD: 2 CONSTRUCTION 



There are certain differences, the main ones being that the 
Scottish engine seats are fitted directly on to the frames, 
checked over each frame and through bolted before planking. 
Hie side floors and filter pieces are lugged to the seats with 
angle irons. In vessels of 80 ft. (24.4 m.) and over die engine 
teats are continued as far forward as practicable in the form 
of side keelsons. The garboard strakes are normally the same 
thickness as the ordinary planking but very much wider and 
the bilge and rubbing strakes are increased in size as shown 
in the drawing. The only woods used in the main structure of 
the vessel are oak and larch, the deck being of pine. The rise 
of floor is also much more pronounced in the Scottish type. 

It will be seen that in the smaller vessels the weight of wood 
is practically the same as in those proposed by Simpson but 
with rather striking differences in various members as shown 
in the sectional drawing attached. 

In the case of Vessel 1 2 however the comparison is very high 
and is higher than that of any other regulation. This is 
accounted for by the double framing, and practically all the 
other scantlings as shown in table 41. 

The Scottish method of double framing is different from that 
of the Danish type as the two frames are bolted together after 
the inside faces have been treated with preservative. When a 
Scantling Numeral of 20,000 and over is reached the horse 
power and weight of the engine necessitates such construction. 

In vessels of 80 ft. (24.4 m.) and over it is becoming general 
practice to fit steel bulkheads and steel beams in way of the 
engine room with steel engine beds and these can be welded 
together to form a strong attachment for the engine. 

The papers by Simpson and Hanson have, Mr. Sutherland 
hoped, started a movement that will eventually lead to more 
discussion and interchange of ideas on this controversial but 
highly important subject. 

In Scotland there is no intention of standardizing the design 
of vessels, as this would be a retrograde step and a bar to 
progress. He was happy to add that the step taken was made 
in consultation with the principal producers' associations and 
with the fullest co-operation and advice of the builders. 
Improvements are bound to come and this can be greatly 
speeded up by the interchange of ideas between naval archi- 
tects and designers. 

MR. J. LINDBLOM (Finland): The scantling proposals sug- 
gested by Hanson and Simpson have been needed for a long 
time. When his shipyard started building, some 15 years ago, 
no scantling tables were available. The conclusion that 
laminated construction of frames is expensive, is not true. 
Frames built for 1,500 boats have been found to be cheaper 
but this depends on equipment used in the construction. It is 
preferable to start from raw material, then build up die 
impregnated material for machining and then build up the 
frames. As regards fastening, bolts with nuts were first used 
but later old fashioned clinch bolts 0.71 in. (18 mm.) were 
introduced. These bohs ate driven cold. Soft materials were 
used and proved to be good. Norwegian pine was used, 
having good absorbing properties for impregnation. It also 
has tensile strength. 



M*. J. C E. CUUMMO (Portugal): In Portugal sawn frames 
are used throughout. The method of construction in which 
both frame futtocks are interrupted at and tenoned into the 
keelson is not practised. Local pine and oak are generally 
used They are not usually of very high quality with the 

[ 



exception of wood coming from a few forests. This leads in 
some cases to the use of increased scantlings. 

He has not yet had time to compare fully the scantlings they 
use in Portugal with those given in the two papers. He would 
only say that in Portugal they would not go below 30 mm. 
(U in.) in hull and deck planking and that beams are very 
seldom placed on the same spacing as frames. Their spacing is 
regulated by the arrangement of hatches and casings. 

Deck camber is generally 1/30 to 1/20 of beam. In some 
cases regulations limiting size of fishing vessels would penalize 
the boats with greater camber. In wood construction they use 
scarphes in keels which agree with the ones indicated by 
Hanson. 

For bulkheads the tongue and groove construction, with one 
thickness of plank, is quite prevalent. Such bulkheads are not 
strictly speaking watertight. On the whole their scantlings 
agree with the "as built figures given by Simpson and not too 
well with the ones given by Hanson. Keels are never square 
in section and keelsons are always practically so. On the 
matter of caulking, he agreed most certainly with Hanson. On 
fastenings, scarphes and bent frames, he agreed with Tyrrell. 

They use and recommend the bilge stringer construction 
mentioned by the Scottish participants. They do not use 
keelsons in their smallest craft and the engine bearers are 
always extended well forward. 

He would point out that standard scantlings, although 
very desirable, can only be worked out in conjunction with a 
table of standards of quality and strength of materials and 
standard methods of construction. Both these standards are 
now unobtainable on an international basis and in his opinion 
that makes the two papers even more important. 

He liked to think that standards could be used to further 
evolution and adaptation to local conditions which vary 
considerably due to service requirements of the vessels and 
wood working habits. He regretted to say that scantling tables 
of classification societies had been used as a rigid law in his 
country. Here was the superiority of Simpson's paper where 
the underlying Working hypothesis was clearly stated and 
allowed for other basis to be applied. 

He felt it was the duty of all participants to provide this 
kind of information regarding their own local standards as 
Hanson and Simpson have done. 

Regarding Simpson's numeral, he would only disagree with 
the use of LOA as a parameter, although it seemed a most 
practical one. 

In Portugal both the Veritas rules are generally followed in 
wood and steel construction and from 130 ft. (40 m.) upwards 
Lloyds or Veritas in steel construction. 

Referring to fig. 120 in Hanson's paper, he presumed that 
the fastenings were merely generally indicated and that 
possibly their details would not exactly correspond to what 
the drawing appears to show. Otherwise he would prefer 
different arrangements. 

DR. O. BORDOLI (Italy): He was pleased to note that from the 
small amount of information given in the various papers, it 
was evident that for hulls of the same type and of the same 
dimensions, the weights of the bare hulls varied quite a bit, if 
constructed according to traditional local methods or the 
various .-government or classification institute regulations. 
Hie reasons for these differences, which it certainly would be 
a food thing to eliminate or at least reduce, are due to the 
varying importance attributed to the different parts of the hull 
structure. 
In a congress in Ancona in 1955, Italian shipbuilders 



SCANTLINGS DISCUSSION 



requested, at his suggestion, that the Rcgistro Italiaao Navalc 
(R1NA) should modify the regulations for wooden construc- 
tion. Adopting the same methods as Gnanadoss, he had now 
been able to conclude that for the construction of a hull of 
similar dimensions as No. 6 of Simpson, using the regulations 
of the Bureau Veritas and the RINA, the weights proved to be 
about 18 and 30 per cent, greater than those foreseen by 
Simpson's scantlings. 

The subject of scantlings is such a vast and complicated 
one that a separate Congress for that purpose is called for. 
Regulations had been drawn up according to tradition in 
different countries, and boats built according to them. It was 
very complicated to compare various specifications, because 
they were based on local rules. 

He agreed with all participants that standardization was 
difficult to achieve because of local conditions, availability of 
timber, labour, etc. The traditions of boat building go back 
thousands of years: if one went back to these traditions, it 
might be possible to obtain some comparisons and evolve 
some standards and then, with suitable coefficients, suggest 
the best scantlings for the respective areas. He knew that 
different emphasis had been attached to various structural 
particulars. 

Strength with economy 

MR. J-O. Traung (FAO) said that it was evident that some 
participants disagreed with Simpson because they had dif- 
ferent practices. If when comparing two successful boats 
built differently one type was built with considerably less 




Fig. 168. Body plan of 78.5 ft. (24 m.) fishing boat in both wood and 
steel version, the steel version having 7 to 9 per cent, lower resistance 



material and both had withstood the hazards of the sea for 
many years, then the lighter one would be the most eco- 
nomical to build. It was important to remember that 
Simpson's proposals were based only on successful boats. 
They might be too heavy but not too light. 

Mr. Traung had first seen the possibility of using steam- 
bent frame construction in large fishing boats when he visited 



EHP values for 



TABLE 43 
strip made of sted and wood 





A= 135 ton 




B 


= 19 ft. (5.8m 


.) 


B 


=21 ft. (6.4m.) 


B-22.9ft. (7.0i 


n.) 




M87 
Wood 


Afl06 
Steel 


Improve- 
ment 


A/66 
Wood 


Af99 
Steel 


Improve- 
ment 


A/57 
Wood 


AflOO 
Steel 


Improve" 
ment 


V 


, 


VP 


Per cent. 


Ei 


IP 


Per cent. 


EHP 


Per cent. 


6 


15.7 


13.8 


12.1 


16.1 


15.3 


5.0 


15.9 


14.3 


10.1 


7 


27.6 


25.3 


8.3 


28.5 


27.3 


4.2 


29.1 


25.8 


11.3 


7.5 


36.8 


33.6 


8.7 


37.7 


35.7 


5.3 


38.8 


34.3 


11.6 


8 


50.2 


44.8 


10.7 


50.0 


46.7 


6.6 


51.9 


45.3 


12.7 


8.5 


66.8 


60.3 


9.7 


66.2 


61.4 


7.3 


68.8 


60.4 


12.2 


9 


85.6 


78.9 


7.8 


84.5 


78.6 


7.0 


88.0 


80.4 


8.6 


9.5 


107.5 


100.4 


6.6 


106.7 


99.0 


7.2 


110.0 


104.0 


5.5 


10 


134.7 


124.8 


7.4 


135.0 


124.9 


7.5 


137.9 


127.5 


7.5 




8.9 


A- 110 ton 


6.3 




8,0 




8.1 






A- 160 ton 


7.8 






7.4 



[183] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



TABLE 44 



50 to 100 ft. (IS to 30 .) 



LOA . . ft. .2 
m. I SUM) 


54.0 
16.45 


59.1 
18.00 


62.3 
19.00 


65.6 
20.00 


68.9 
21.00 


73.8 
22.50 


77J 
23.70 


78.7 
24.00 


82.0 
2540 


91.8 
28.00 


98.5 

30.00 


LP . . ft. 43.0 
m, 1340 


47.7 
14J5 


52.5 

16.00 


55.6 
16.97 


58.1 
17.70 


62.0 
18.90 


63.5 
19.35 


68.7 
20.95 


71.2 
21.70 


73.1 
2X27 


83.4 
25.40 


88.6 

27.00 


Bvmdtfa, moukUd ft. 13.5 
m. 4.10 


15.4 
4.70 


16.7 
5.10 


17.4 
5.30 


17.7 
5.40 


18.4 
5.60 


19.0 
5.80 


19.0 
5.80 


19.7 
6,00 


20.7 
6.30 


21.3 
6.50 


21.7 
6.60 


* " 2: % 


7.1 
2.15 


7.5 
2.30 


8.0 
2.45 


8.2 
2.50 


9.0 
2.75 


9.0 
2.75 


9.0 
2.75 


9.8 
3.00 


10.7 
3.25 


10.7 
3.25 


11.5 
3.50 


D -""- ft & 


5.9 

1JO 


6.6 
2.00 


7.1 
2.15 


12 
2.20 


8.2 
2.50 


1.2 

2.50 


8.2 
2.50 


8.5 

2.60 


9.8 
3.00 


10.2 
3.10 


10.8 
3.30 


Grata toon*** (74.5 A. or 
23.10 m. and upward! 
withctoMdwhakbtck) 21.40 


32.50 


42.83 


46.34 


52.48 


63.59 


67.14 


85.73 


91.80 


110.67 


129.80 


155.60 


. BHP 50 


80 


100 


120 


135 


150/180 


200/250 


250/320 


250/320 


375 


450 


500 


. r.p.m. 320 


350 


320 


350 


350 


750/300 


750/300 


750/300 


750/300 


750/300 


750/300 


750/300 


SpMd . . knots 8 


8 


s* 


9 


9 


91 


9| 


H/IO 


9|/10 


10 


m 


10* 


Stem (beno*d plate) mm. 7 


8 


8 


8 


8 


9 


9 


9 


9 


9 


9 


9 


Sternpott . . m. 75x25 


100x45 


100x50 


100x50 


100x50 


125x50 


125x50 


125x50 


125x50 


125x54 


125x60 


125x63 


BaffcMl (with bulb) 150x8 


150x8 


180x10 


180x10 


180x10 


180x10 


180x25 


180x25 


180x25 


180x25 


200x25 


200x25 


BU*kMfe (with bulb) 150x7 


150x7 


180x8 


180x8 


180x8 


180x8 


180x8 


180x8 


180x8 


180x8 


200x8 


200x8 


RtidderbMd . 65 


80 


85 


90 


90 


90 


95 


100 


100 


105 


115 


125 


RudderpUtw . 6 


6 


6 


6 


6 


6 


6 


8 


8 


8 


8 


8 


XMiptete . . M 7 


7 


7 


8 


8 


8 


8 


8 


9 


9 


10 


10 


Shemtrake . . 6 


7 


7 


8 


8 


8 


8 


8 


8 


8 


10 


10 


Other shell plates . 6 


7 


7 


7 


7 


7 


8 


8 


8 


8 


9 


9 


Bulwark . . 5 


5 


5 


5 


5 


6 


6 


6* 


6* 


7 


8 


8 


Steel deek . . 5 


6 


6 


6 


6 


6 


6 


6 


6 


6 


6 


7 


Wooden deck (teak) 60 


60 


60 


60 


60 


65 


65 


65 


65 


65 


65 


65 


Bulkheads . . 6 


6 


6 


6 


6 


6 


6 


6 


6 


6 


7 


7 


Bulkhead* tower plate,. 6 


7 
65x50x6 

700 


7 
65x50x6 

700 


7 
65x50x6 

700 


7 
65x50x6 

700 


7 
75x50x7 

700 


7 
75x50x7 

700 


7| 
75x50x7 

700 


7* 
75x50x7 

700 


7* 
75x65x7 

700 


8 
90 x 65 x 7 

700 


8 

90 < 65 8 

700 


700 


Floors . . .300x5 


300x5 


350x6 


350x6 


350x6 


350x6 


350x7 


330x7* 


350x7 


350x7 


380x8 


400x8 


Frames . . 50x50x6 


65x50x6 


65x50x7 


65x50x7 


65x50x7 


75x50x7 


75x50x7 


75x50x7 


75x50x7 


75 x 65 x 8 


75x65x8 


90x65. 8 


Frame spacing - 450 


450 


450 


450 


450 


450 


450 


450 


450 


450 


450 


450 


Deckbeams . . 65x50x6 


75x50x6 


75x50x7 


75x50x7 


75x50x7 


90x50x7 


100x50x7 


100x50x7 


100x65x7 


100x65x 


8 100x65x8 


100x65 8 



Hanson in 1948, and learnt that these boats had a lifetime of 
over 30 years. The boats in his home country, built of sawn 
frames, did not all last so long. He had come to the conclusion 
that steam-bent frame construction was superior. Many 
seemed to think that a frame should have a big section 
modulus. Mr. Traung felt that a frame should not be 
regarded as a beam, but rather as a tie rod something which 
kept die planking togetherand a very flat section of the 
steam-bent frame as suggested by Chapelk might be suitable/ 
in fact, smaller boats have been built with stainless steel tie 
rods inside the planking, which thus forms a true arc con- 
struction. 

Builders of wooden boats were feeling increasing competi- 
tion from builders of steel ships, the construction of which 
had been very much simplified during die last few years. 
Welding, for instance, had developed with the use of covered 
electrodes and with cheap welding equipment. Mr. Traung 
felt that the builders of wooden boats should drop their con- 
servative attitudes and study die practices of other countries, 
with a view to improving their own methods. Only in this 
way could they hope to produce boats which were cheaper 
than those constructed of steel. 



Scantlings were important, not only to builders and owners 
of fishing vessels, but also to FAG, for FAO aimed at cheaper 
fish production, which could be achieved by building cheaper 
fishing vessels. If there were no competition from steel ships, 
it would not matter from the wooden boatbuilding point of 
view whether the vessels were built heavy or not, so long as all 
builders gave the same quotations, but it made a big difference 
to both the fisherman and the consumer if there was also 
unnecessarily heavy initial investment. 



RESISTANCE OF WOODEN KEEL, STEM AND 
STERN POST 

MR. W. HENSCHKB (Germany): Hanson showed that it is 
important to have a strong keel and corresponding stem and 
stern post to give wooden boats a good strength. He agreed 
with this but wanted to draw attention to the fact that 
resistance and propulsion characteristics also have to be con- 
sidered. In the modd tank at Berlin-Potsdam he had made 
tests with wood and steel 78.5 ft. (24 m.) fishing boats having 
the same dimensions and shape. The models were made to the 
scale of 1 to 10. According to fig. 168 the difference consisted 



[184] 



SCANTLINGS DISCUSSION 



only in the type of keel, stem and stern post. In spite of com- 
paratively small differences, the steel boat had, according to 
table 43, as an average, 7 to 9 percent, smaller resistance than 
. the wooden boat (these results have also been given in FAO 
Fishing Boat Tank Tests, Part II). Later resistance and self- 
propulsion tests were made with a model of scak 1 to 8 and it 
was found that the propulsive efficiency of the steel boat was 
some 10 to 20 per cent, higher than that of the wooden boat. 
He felt that the wooden boatbuilder should consider these 
results and endeavour to obtain the best combination of 
strength and resistance such as fairing stem and stern posts. 

STEEL SCANTLINGS 

MR, W. ZWOLSMAN (Netherlands) referred to Hanson's paper, 
which gave minimum scantling dimensions of steel boats, and 
suggested that a further list of scantlings based on many years 
of actuaf practice might be useful. 

Table 44 indicates scantling dimensions that are also 
approved by Lloyd's Register of Shipping and Bureau 
Veritas. All the construction drawings of the fishing craft 
built by his firm have been approved by one of these classifica- 
tion bureaus or by both. If the boats are to be supplied with a 
certificate for ice-reinforcement, the shell plates must be 
.02 to .04 in. (i to 1 mm.) thicker. 

A comparison of this specification with Hanson's shows 
that the shell plates are somewhat heavier and the frame 
distance somewhat smaller. 

Owing to the heavier shell plates it has never been necessary 
to apply longitudinal frames. Heavier shell plates also are 
found to prolong the life of the boats considerably. 

As per the prescriptions of the Shipping Inspection or the 
insurers, the shell plates must be renewed if wear and tear 
have reduced their thickness to .16 in. (4 mm.), and obviously 
if shell plates .32 in. (8 mm.) instead of .24 in. (6 mm.) thick 
are applied, it will be twice as long before the critical limit of 
.16 in. (4 mm.) is reached. These heavier shell plates have only 
little influence on the overall cost price of the boat. 

REPLIES OF AUTHORS 

MR. H. C. HANSON (U.S.A.): His paper suggested a minimum 
standard scantling table based upon actual usage in thousands 
of vessels that had been built throughout the world, boats 
now in operation having been built along these standards as 
long ago as 60 years. So far as preservatives for wood were 
concerned, he was of the opinion that anything that penetrates 
the wood is good, but that anything forming a coating over 
the wood where moisture is encased is not good, since this 
forms a rot condition. 

Air circulation and the use of salts are recommended. The 
use of sawn frames fore and aft in a bent oak frame boat are 
necessitated because the shapes require it, builders will try to 
bend the frames and they crack, so to overcome this they split 
the bent frame, which he considered bad practice, because 
experience shows that rot will occur between the two split 
members. The use of deep floors is good, not only for the 
strength they give the vessel, but in smaller vessels the tonnage 
measurement is reduced which is an advantage in some 
countries. Chapelle's statements that boats should be built 
and used only in the areas where the wood itself grows, for 
longevity, he did not agree with, one has only to see the many 
wooden vessels built in the Southern parts of U.S.A. from 
the Northwest firs to refute this statement. He agreed with 
Chapelk that the use of independent top timbers is good, but 
more costly; Mr. Hanson had shown the frames extended to 
form bulwarks because one pays for the oak to bend the 



frames, and thus he had shown this construction for eco- 
nomical reasons. Iron bark sheathing over soft wood plank- 
ing is used in the Pacific Northeast, in constrast to the use of 
solid hardwoods for planking as mentioned for Iceland, and 
he believed the sheathing method was better and more eco- 
nomical and easier repaired. 

Mr. Hanson agreed that the steel engine bed for a wooden 
vessel is superior construction, he had used steel engine beds 
for years and had used steel bulkheads in coqjunction with 
them tieing the engine bed to bulkheads at ends of engine 
room, and he found this reduced vibration and made a better 
vessel for upkeep costs. 

The use of clinch bolts in wooden vessels was discontinued 
at the end of World War I; they do not do a good job, and as 
soon as the wood shrinks around them nothing can be done 
about it. By using screw bolts one is able to cinch them up at 
any time, and before delivery of any vessel it is common 
practice now to cinch up on the screw bolts, after wood has 
dried out while building. Even on vessels several years old 
one can take up on these screws. 

Hook scarphs will do the job all right, but they are costly to 
make and Mr. Hanson saw no purpose whatsoever in using 
them, as the many thousands of vessels built from his plans 
never had any and neither did the 60-year-old vessel above 
mentioned. Also since there is some pretty heavy weather 
throughout these Pacific areas, he considered money spent on 
lock scarphs, lock dowels a waste of time and money. Lock 
strakes come under the same category of waste. 

MR. DWIGHT S. SIMPSON (U.S.A.): Since so many variations 
of Numerals have been offered with a number of suggestions 
seeming a bit wide off the mark, Mr. Simpson thought it well 
to repeat and amplify some of the statements in his paper. 

The paper was an attempt to develop by analysis of existing 
fishing vessels, minimum scantlings for the construction of 
fishing vessels but not freighters, sailing yachts or motor boats. 
They were not intended to be used without judgement; 
however since the prototype vessels serving the analysis have 
existed for many years in North Atlantic waters from Hatteras 
to the North of Newfoundland about as tough an area as 
can be found anywhere sound judgement might, of course, 
increase scantlings for Arctic use or decrease the same for less 
arduous spots of the world. 

It was known that most fishing vessels are still built from 
models, or even from rule of thumb, with no plans available. 
Therefore, basic dimensions that required no plans or engineer- 
ing skill to obtain were chosen. 

Length (LOA) was taken as overall length simply because 
most fishermen and many builders know and talk no other 
length. Length on the waterline may vary with the loading and 
trim. Length between perpendiculars is no nearer estimate of 
the vessels size than length overall, and would have to be 
explained to many owners and builders. 

Breadth (B) over the planking is easy and universal 

Depth (D) amidship from top of deck at side to the rabbet 
line is easy to obtain and a better measure of size than if 
taken to top or bottom of keel or top of floors (Hanson 
mentions the use of deep floors to reduce tonnage measure- 
ment, for instance). 

Mr. Simpson thought that perhaps not enough had been 
said about the effect of varying prismatic coefficient. Again 
remembering that the paper dealt with fishing vessels, the 
limits of the prismatic appear to be between ,58 and .68. 

If the 85 ft. (25.9 m,) vessel No. 12 were designed to these 
limits, maintaining the same displacement she would have 



[185] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



midship coefficient between .791 and .680 or areas between 
96.4 14, ft. (8*95 sq, m.) and 82.8 sq. ft. (7.7 sq. m.). These 
sections give half girths of 15.23 and 16,06 ft. (4.65 and4.9m.), 
a difference of .415 ft. (.126 m.) or 2.66 per cent from the 
average of the two. Applying this differential to the calcula- 
tion of the numeral, the minimum FxN will be 1,079 and the 
maximum 1,192. Entering the chart, fig. 147, Z minimum 
wiH be 16 and Z maximum 17.55 and from fig. 148 the 
minimum frame section will be 3.65 x 6.28 in. (93 x 160 mm.) 
and title maximum section 3.82 x 6.57 in. (97 x 167 mm.). Both 
of these would likdy be transformed by the builder into 
3t x 6i in. (95 x 160 mm.), or perhaps 6 in. (165 mm.). 

Again, an examination of 60 vessels from all parts of the 
world show a minimum midship section coefficient of .641 
and a maximum of .900 (both are extreme and rare), which 
give half girths of 15.21 and 17.86 ft. (4.65 and 5.45 m.) or 
8 per cent, from the median. Applying this differential as 
before to the F formula gives a minimum section of 3.35 x 
6 in. (85 x 152 mm.) and a maximum of 3f x6J in. (98 x 
165 mm.). These are so close to the 3f x 6 in. (95 x 1 60 mm.) 
obtained from the unmolested rule that it seems not worth 
white to further complicate the numeral calculations. 

White a number of rules use the R or diagonal extension 
factor, it would appear from the above that it matters little, 
especially since fishing vessels with large midship sections seem 
to have small prismatics and vice versa. The American 
Bureau of Shipping uses a block coefficient at .8 x D which 
clearly fixes the capacity and, of course, makes it necessary to 
have a completed lines drawing. The original list of prototype 
vessels would be greatly reduced owing to lack of lines and a 
new list established before calculating a new set of graphs, 
and Mr. Simpson again wondered if the game is worth the 
candte. If these formulae become so complicated that many 
would close the book after a partial glance and go on building 
in their accustomed manner what has been gained? 

The paper requested that timbers from other countries be 
related to those listed. Only Swinfteld has complied and it 
would be valuable if he had included more varieties and more 
details. Mr. Simpson believed the controlling properties 
would be specific gravity, resistance to rot, and obtainable 
size. For vessels of 75 ft. (22.9 m.) and smaller, bending 
properties would be valuable. Teak was not included in the 
original list since it is not a fishing vessel timber in the North 
Americas. 

Tyrrell and others question the position allotted to larch, 
but he is talking of the European larch (larix decidua). The 
US. Western (larix occidental**) and Eastern (larix larfcina) 
larches are very different and generally yield a brash timber 
and, except for the roots from which the old "hackmatack" 
ship knees were hewn, am almost unknown in shipbuilding. t 
Mr. Simpson was surprised at the universal antagonism 
shown against the round spike and wondered if a square drift 
or bolt is in universal use in other parts of the world. He 
thought it strange that minds able to accept complicated 
mathematical formulae and model basin tests as criteria for 
food hull design baulk at equally good mathematics and 
laboratory tests as criteria for good fastenings. Obviously 
there is no reason exc^t custom for the feeling. Simply to say 
that fig. 1 53A (used almost exclusively in the North America 
for more than 100 yean) or fig. 154D (used by the best boat 
ttd shipbuilders for 20 or 25 years) "are unfit for fastenings" 
or that 'the square fastening is to be preferred" is not a 
satisfactory answer in the face of technical and practical 
eApei fence to the contrary* 



Tyrreirs standard spike was once largely used as a ctenche 
nail bat is now largely succeeded by the wood screw. The 
long life of his sample is, of course, due to the purity of the 
metal and the excellence of the galvanizing. 

McGruer's fluted "Belgian" nail seemed to hold well in 
withdrawal but appears weak in lateral resistance. It also 
might be expensive. 

With some experience of structural testing, Mr. Simpson 
was of the opinion that Hamlin has outlined a program so 
extensive and costly that none but a Government or wealthy 
Foundation could finance it. The results would have a quali- 
tative value but otherwise might have to wait until some sort 
of strain measurements were devised and tried on parts of 
many hulls in service. 

Hamlin and others desire the rutes to be extended to smaller 
boats and bent frames. The paper by Smith (1950), already 
referred to, covers the subject quite well with reference to 
U.S. West Coast construction. 

Experience has shown that, at least up to 75 ft. (22.9 m.) 
or so, a well-built bent frame vessel is at least the equal of 
sawn frame construction in ability to stand grief. Glued 
laminated bent frames have been used in U.S. Navy vessels 
as large as 165 ft. (50.3 m.), with satisfactory results, but they 
are not troubled with large and varying loads. 

Bardarson, Gnanadoss and Sutherland have laboured 
mightily in a good cause and their efforts serve well to show 
the need of further study of the scantling problem. 

If Bardarson's 75 GT vessel is compared with Mr. Simpson's 
slightly larger vessel No. 12 in Gnanadoss's table 36, it is 
found to be 68.6 per cent, heavier than Mr. Simpson's 
formulae; 32.8 per cent, heavier than Bureau Veritas; 32.5 per 
cent, heavier than Swedish; 28.3 per cent, heavier than New- 
foundland. Sutherland would rate it 22 per cent, heavier 
than the White Fish Authority rule. This is indeed a heavy 
vessel, sacrificing many tons of pay load at some considerable 
expense. It seems added proof that the subject under dis- 
cussion is well worth pursuing. Icelandic waters cannot be so 
severe as to justify such heavy scantlings if they were so 
severe, the GM and GZ of the Icelandic vessels could not be as 
low as they are. 

Takagi's graphs are extremely interesting and will be of 
great assistance in the final analysis. His fig. 161 and question 
recall the statement in the paper than no New England or 
Nova Scotia trawler has planking less than 1} in. (38 mm.) 
finished thickness and possibly a revision of the figures would 
develop 3 in. (76 mm.) finished planking for an N of 8 instead 
of 7. It is interesting to find the Simpson rule in the middle, 
more or less, of the several proposed Japanese rules. 

In Mr. Simpson's opinion the keels of his vessels, both 
existing and rutewise, are much too heavy structurally. It 
must be remembered that all these vessels handle their nets 
from the side and the necessity of holding the vessel against 
drift white bringing in the net accounts for the depth of keel. 
He has added box keels of wooden keel dimensions to several 
steel trawlers, improving their handling of the net immensely, 
and has just completed a design of a 1 10 fit. (33.5 m.) steel 
dragger with such a keel. 

Answering Takagi's third question, Mr. Simpson said that 
the section modulus per foot of ship's length of beams as for 
frames is simply Z of the beam divided by spacing in inches 
multiplied by 12. In this connection it should be noted that 
beams should be spaced to suit bulkheads, hatches and deck- 
houses but kept as close to standard as possibte. If a different 
spacing is wanted the chart gives it, However, in spite of 
comments, the closer the beams are spaced the smaller and 



[1*6] 



SCANTLINGS DISCUSSION 



cheaper they are. Experience shows that with small spacing 
the expensive knees are not required tor long life. 

To Zimmer's question, Mr. Simpson stated that U.S. 
North East coast vessels are sheathed only to protect the 
planking from surface ice and the banging of the doors. He 
would like to see details of Zimmer's concrete keelson. 

The suggestion that all standard specifications be collected 
in one volume is good but might make it harder for the novice 
to make up his mind. He therefore preferred the idea of a 
world-wide committee to collect and analyse the various rules 
in an attempt to revise the formulae and suggested variations, 
other timbers, etc. 

He noted that Sutherland's fig. 167 apparently shows single 
frame futtocks with long butt straps for the smaller vessels 
but believed that double futtocks of lighter scantlings would be 
a lighter and stronger frame. 

Sutherland's engine bed seemed very deep and subject to 
vibration. The crossing of the keelson with secondary floors 
would stiffen the hull under the engine, decrease the size of 
the engine bed, and minimize vibration. 

Mr. Simpson agreed with Chapelle's remarks on bent 
frames except for the preference for thin frames. Most Nova 
Scotia small craft are built this way and invariably show many 
broken frames after short use. Thin frames offer little bury 
for ordinary spikes; clench nails are unreliable, being subject 



to rust and breaks at the bend ; rivets and screws are expensive* 
With proper equipment there is no great trouble in bending 
3 in. (76 mm.) stock. If thicker is required it could be laminated 
with added strength. 

Mr. Simpson took issue with Traung, believing that it does 
matter to the trade whether a boat be light or heavy. The 
lighter vessel saves both timber and labour and carried more 
load. It should sell for less and easier, and would tend 
perhaps to more boatbuilding. 

He agreed with Traung that frames could be reduced, even 
perhaps, dispensed with if planking could be made a mono- 
lithic unit such as can be achieved by double or triple planking, 
by glued strips or edge fastening. (He has seen 40x8 ft. 
(12.2x2.4 m.) dugouts with no framing). For hundreds of 
years large Chinese junks have been built with no frames, 
just intermittent cleats holding three or four planks together 
plus a unique method of edge fastening the planks. As long 
as the skin consists largely of individual planks transverse 
strength must be achieved by frames and under this stress 
they could be likened to beams. 

Mr. Simpson hoped that Swinfield can be persuaded to 
expand his thoughtful remarks, with more information on 
Australian scantlings and timbers. He also joined the majority 
of discussers in the hope that FAO can arrange a further re- 
search into the possibility of more uniform basic scantlings. 



[187] 



GLASS REINFORCED PLASTIC HULLS 

by 
PATRICK D. DE LASZLO 

The paper dealt with plastic hulls and decks made from cold setting polyester resin reinforced with glass fibre "mat" laid up in a 
female mould. The chief advantages of plastic hulls are low initial cost and very low maintenance and repair costs. One hull costs no more 
than an equivalent wooden hull but several hulls from the same mould are cheaper than wooden hulls. Maintenance costs are low because 
plastic hufls are unaffected by sea water; they cannot warp, rot, or split like wooden hulls. They are dry because they are homogeneous and 
therefore will not open at the seams or leak. They cannot rust or corrode and they are not subject to galvanic action like aluminium, nor are 
they attacked by marine borers. They do not absorb water, therefore they cannot be contaminated by fish nor will they add to their own 
weight by water absorption like a wooden hull when they are launched. Plastic hulls do not have to be painted. The colour is impregnated into 
the resin at the time of manufacture. The colour can, however, be changed if desired by sanding down and painting with a suitable paint. 
Plastic huH can be made fire-resistant. They are stronger than wooden hulls of the same weight and have greater resistance to impact. They 
are nrifiant and do not dent under impact. If a plastic hull is damaged in a collision the damage will be local that is to say there are no 
planks to iplit A first-aid repair can be carried out in a matter of hours and a full-scale repair takes less than one-tenth of the time required 
to repair a wooden hull. Plastic is a natural insulator and therefore will not sweat internally like metal. The largest plastic hulls in the world 
are built under Lloyd's survey, with bulkheads, tanks and engine foundations installed while the hulls are still in their moulds. 

LES COQUES DE PLASTIQUE RENFQRCE DE FIBRE DE VERRE 

La communication traite des coques et ponts de plastiquc fabriques avcc de la resine de polyester prenant a froid, renforcee par 
des matelas de fibre de verre Stales dans un moulc creux, Lea principaux advantages des coques de plastique sont le coOt initial bas et Ics tres 
faibtos expenses d'entrctien et de reparations. Une coque de plastique ne coOtc pas plus qu'une coque tquivatonte de bois, mais pluskurs 
coques sorties du meme mouto cotitent moins cher que des coques de bois. Les frais d'cntrcticn sont faibles parce que les coques de 
plastique ne sont pas affectecs par I'cau de mer: elks ne peuvent ni gauchir, ni pourrir ou se fendre comme les coques de bois. Elles sont 
stehes parce qu'elfes sont homogenes et ainsi ne s'ouvrent pas aux joints et ne fuicnt pas. Elles ne peuvent pas rouillcr ni se corroder ni 
etre attaquees par les organismes perforants marins, et cites ne sont pas sujettes & Faction galvanique comme 1'aluminium. Elles n* absorbent 
pas f eau : ainsi dies ne peuvent pas etre contaminees par le poisson et tour proprc poids ne peut pas ctre augment* par absorption d'eau comme 
une coque de bois quand elks sont lancees. II n'est pas ntoessaire de peindre les coques de plastique. La resine est imprtgnee de colorant 
au moment de la fabrication. Cependant, on peut changer la couteur si on le desire, en sablant la coque et en la pcignant ensuitc avec une 
peinture appiopriee. Les coques de plastique peuvent &tre rendues resistantes au feu. Elles sont plus robustes que les coques de bois de 
meme poids et ont une plus grande resistance aux chocs. Elles sont dastiques et ne se bosstlent pas sous le choc. Si une coque de plastique 
est endominagee dans une collision, les dgats sont tocauxc'est&-dire qu'il n*y a pas de planches de bordd qui se fendent. Une reparation 
urgente peut etre effectuee en quelqucs heures, et une reparation normale prend moins d'un dixieme du temps n6cessaire pour riparer une 
coque de bois. Le plastique est un isolant naturel, done il ne transpire pas a I'intdricur comme le metal. Les plus grandes coques de plastique 
du monde sont construites sous to contrdto du Lloyd's, les cloisons, les reservoirs et les fondations du moteur etant installed alors que les 
coques sont encore dans tours moutos. 

CASCOS DE MATERIAL PLAST1CO REFORZADO CON FIBRA DE V1DRIO 

Trata esta ponencia de los cascos y cubtortas de materiatos pttsticos fabricados con resina de pollster de fraguada en frio, rcforzados 
con paltotes de flora de vidrio extendidos en un molde hueco. Las principatos ventajas de los cascos de plattico son su costo inicial bajo y los 
pequeftos gastos de mantenimiento y reparation. Un casco de plastico no cuesta mas que uno equivatonte de madera, pero varios cascos 
hechos con el mtsmo molde son mas baratos que los cascos de madera. Los gastos de mantenimiento son bajos porque a los cascos de plastico 
no les afecta el agua del mar: no se pueden alabear, ni pudrir, ni rajarse como los cascos de madera. Son secos porque son homog6neos y, 
por tanto, no se abren en las juntas ni se hacen vias de agua. No se pueden oxidar ni comer y no estan sometidos a la accidn galvanica, 
como el aluminio, ni pueden ser atacados por los takdradores marine*. Como no absorben agua, no los puede contaminar el pescado ni 
aumentara su propio peso por absorddn de agua como aumenta el de un casco de madera cuando se bota. No hay que pintar los cascos de 
plastico. La resina se impregna de colorante en d momento de la fabricacion, pero si se desea cambiar d color, se puede hacer raspando el 
casco con arena ypintAndob con unapinturaapropiada. Se puede hacer que los cascos de plastico resistan el fuego. Son mas robustos que 
los cascos de madera del mismo peso ytienen mayor resistendaaioschoques. Son elastkx* y TO se abollan al chocar. Si un casco de piastico 
sufre averias en ana cotillon, los dafios son locales, es deck, no hay planchas que se poedan romper. Una reparation urgente se puede haoer 
en unas pocas boras y una reparation normal tarda menos de la decima parte dd ttompo necesario para reparar un casco de madera. El 
pUkitico es un aWante natural que no traniptra en d interior como d metal. Los mayoret catcot pttetlcos dd mundo se construyen bajo la 
tnspeocion de k Lloyd's y tot mamparos, los tanques y las bases dd motor se instalan mtontras lot cascos ettan todavia en los moldes. 

[188] 



NEW MATERIALS PLASTIC HULLS 



GLASS reinforced plastic can be used for making 
the hulk and decks of all vessels and in par- 
ticular fishing vessels up to 130 ft. (40 m.) in 
length. Glass reinforced plastic in this context means a 
laminate made of several layers of 2 oz./sq. yd, (68 gr./ 
sq. m.) glass fibre "mat" impregnated and bonded 
together with cold setting polyester resin. For conveni- 
ence, this type of glass reinforced plastic is referred to as 
Polyester/Mat or P/M. 

Hie raw material! of Polyester/Mat [P/M] laminate 
The chemistry of cold setting polyester resin is outside 
the scope of this paper. It is now produced by a number 
of manufacturers. The resin is an almost colourless 
liquid which can be stored for considerable periods in a 



Method of mmkiag lamiate 

The process by which glass mat is laid into a mould and 
impregnated with polyester resin so as to form a Poly- 
ester/Mat (P/M) laminate is generally referred to as a 
"wet lay-up". The surface of the mould is first treated 
with a separating agent such as wax to ensure that the 
laminate cannot stick to the mould. A "skincoat" is 
then applied by painting or spraying the surface of the 
mould with a film of polyester resin which will eventually 
become the outside surface of the laminate. This film of 
resin is generally coloured. 

The next stage is to apply a layer of glass scrim and 
resin. Glass scrim is a very loosely woven cloth similar 
to the cloth used for covering bacon. 

When the scrim coat has hardened, successive layers 




Fig. 170. Section through a wood mould for plastic construction 



cool place. The resin is activated by the addition of small 
quantities of two other chemicals, generally known as 
the "accelerator" and the "catalyst", which cause it to 
set hard in a predetermined time. After the resin has set 
it will continue to harden over a period of about four 
weeks. For the purpose of building boats it is usual to 
arrange for the resin to set in 30 minutes. 

Glass mat is made of short lengths of glass threads 
disposed at random and loosely held together like a very 
coarse felt. Glass thread is composed of glass fibres each 
of which is about one-tenth of the thickness of a human 
hair. These fibres are astonishingly strong and flexible. 
Comparative tensile strengths are: 

Glass fibre : 1 80,000-300,000 Ib./sq. in. 

( 12,650- 21,000 kg./sq. cm.) 
Cotton : 59,000-124,000 Ib./sq. in. 

( 4,150- 8,700 kg./sq. cm.) 
Nylon: 65,000-1 17,000 Ib./sq. in. 

( 4,560- 8,200 kg./sq. cm.) 
Silk: 68,000 Ib./sq. in. 

( 4,770 kg,/sq. cm.). 



of 2 oz, glass mat, impregnated with resin, are applied 
until the required thickness has been achieved. 

Each layer of glass mat will weigh approximately 
4 Ib./sq. yd. (3 Ib. of resin and 1 Ib. of mat), or 2.17 kg./ 
sq. m. and will be approximately ^ in. (1.6 mm.) thick. 
Hulls less than 30 ft. (9.15 m.) long require only three 
layers of mat which means that they will be about ^ in.* 
(4.75 mm.) thick; 30 to 40 ft. (9 to 12 m.) long hulls are 
4 to 5 layers thick, 40 to 56 ft. (12 to 17 m.) long hulls 
are 6 to 7 layers thick, and hulls 57 to 80 ft. (17.4 to 
24.5 m.) long are 7 to 10 layers thick according to the 
purpose for which they are to be used. 

Moulds 

Hulls are laid up inside a female mould. The mould 
itself can be made of P/M by first making an exact model 
of the hull and then laying up the P/M mould over the 
model. This is convenient for complicated shapes such 
as deck-houses or where a great number of hulk are 
likely to be taken from the same mould. 
It is, however, cheaper and quicker to build moulds of 



[189] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



timber. The frames of the mould are cut from timber or 
steel to the outside shape of the hull at, say, 2 or 3 ft. 
<0.6 to 0.9 m.) stations down the length of the hull. 
The frames are mounted in a cradle built of steel or 
timber Fore and aft 2x2 in. (50x50 mm.) wooden 
"ribbands" are secured to the inner face of the frames 
at about 5 in. (127 mm.) intervals. 

The working surface of the mould is made of plywood 
secured to the ribbands. The inner surface of the ply- 
wood is then carefully sanded and painted. The outside 
finish of the hull will depend on the care taken to finish 
the inside surface of the mould. If proper care is taken 
when finishing the mould the surface of the P/M hulls 
will be equal to first-class paintwork. 

A mould must be made in at least two parts so as to 
enable the hull to be removed, ft is convenient if the 




Fig. 171. A polyester/glass mat hull made in a wood and plaster 
master mould. The 2 halves of the mould have been separated but the 
hull has not yet been removed from the mould. Note the surface of the 
mill which Is highly polished as It comes out of the mould. Note also 
the moulded spray chine 



transom can be removable and the main mould must be 
split down the centre line. The various sections of the 
mould are mounted on rollers so that they may easily be 
separated, see fig. 170 and 171. 

Tenperatore control 

A large hull may take several weeks to build: a 56 ft. 
(17 m.) hull takes about 15 working days. It is therefore 
important that they should be built in a temperature- 
controlled building so that the temperature may be held 
constant day and night, otherwise there will be a dif- 
ference in shrinkage in the various layers which will lead 
to strains and possible delamination. 

Temperature control is unnecessary for very small 
boats, such as dinghies and small sailing boats, because 
the thickness of the hull is generally far greater than is 
necessary for strength, but with large hulls temperature 
control is of vital importance in order to avoid the risk 
oft trains within the laminate caused by variable shrinkage. 



Otter kMs of laminate 

It is possible to make laminates with glass cloth which 
have much higher tensile strength than laminates made 
with mat, but glass cloth is not suitable for boats because 
the resulting laminate is expensive, the high tensile 
strength is unnecessary, and glass cloth will easily 
delaminate if the surface is damaged. 

Laminates can be made with other kinds of resin, in 
particular various kinds of "heat setting** resins, but they 
are not suitable for very large mouldings, like boat hulls 
which may weigh several tons, because it is not practical 
to heat such large moulds. 

Many experiments have been carried out in the U.S.A. 
and U.K. with the object of making hulls of "sandwich" 
construction. A fibre glass "honeycomb", or some kind 
of "foamed" plastic, is sandwiched between an inner and 
an outer layer of glass cloth. The object is to produce a 
laminate which is light and rigid. 

This sandwich technique has proved valuable in other 
fields such as radomes for aircraft, and it is sometimes 
convenient for small boats with flat bottoms, such as 
pontoons, but it is not yet satisfactory for large hulls 
because the tensile strength is inadequate; it is consider- 
ably more expensive than a P/M laminate; it is a great 
deal more difficult to repair, and, finally, it is difficult to 
inspect a sandwich laminate so as to ensure that it is 
effectively bonded. 

Inspection 

It is essential that large plastic hulls should be carefully 
inspected during construction. The largest P/M hulls 
in the world are built in the U.K. under Lloyd's survey, 
and the surveyor must have an easy means of ensuring 
that the quality of a laminate is up to specification. 

It takes about 15 to 20 min. to lay 10 sq. ft. (1 sq. m.) 
of P/M. The resin can be made to set in about 30 min.; 
therefore, there is a clear 10 min. before the resin hardens 
after the operator has finished. It only takes an inspector 
2 or 3 min. to examine the area, which leaves plenty of 
time to remove any air bubbles which he may detect. 

Air bubbles can easily be seen if the resin is not 
coloured. For this reason it is customary to add colour- 
ing matter only to the outside skin of a large hull and to 
lay on subsequent layers of 2 oz. (56 g.) mat with 
colourless resin. 

A P/M laminate can be inspected piece by piece and 
layer by layer but it is never easy to be sure what is 
happening inside laminates made with heat setting resins 
or laminates of "sandwich" construction. It must be 
emphasized that in addition to inspecting each square 
piece of P/M as it is laid, it is necessary to have the full- 
time services of a laboratory to test every batch of mat, 
and every consignment of resin. It is also necessary on a 
large hull to test samples of the laminate as it hardens 
in order to make sure that it is fully "cured". 

If the resins are not of the correct specification, or if 
they are not correctly mixed, or if the temperature condi- 
tions vary, it is possible that a resin may apparently 
harden satisfactorily but will never fully cure. In these 



[WO] 



NEW MATERIALS PLASTIC HULLS 



conditions the resin will gradually "leach" out of the 
laminate and within a comparatively short time the whole 
structure will become dangerous, 

Strength 

The tensile strength of polyester resin by itself is about 
8,000 to 9,000 Ib./sq. in. (560 to 635 kg./sq. cm.). After 
it has been reinforced by 2 oz./sq. yd. (56 gr./sq. m.) 
glass mat, the minimum tensile strength of the resulting 
laminate is 15,000 Ib./sq. in. (1,050 kg./sq. cm.). The 
mat is composed of glass threads disposed in all direc- 
tions, therefore the laminate will have this tensile strength 
in all directions. 

Most boats less than 130 ft. (40 m.) in length are built 
of wood because it is cheaper than steel or aluminium. 
Therefore, P/M shall be compared with wood. 

The tensile strength of wood is 4,000 to 10,000 lb./ 
sq. in. (280 to 700 kg./sq. cm.) along the grain, and 
negligible across the grain. Needless to say, the tensile 
strength of wood used in building a hull is seriously 
diminished by the fastenings and by the fact that the 
grain often "runs out", whereas in a P/M hull there are 
no fastenings and the tensile strength is uniform. 

The specific gravity of P/M is approximately 1.6. 
The specific gravity of a wooden hull, including the 
fastenings, will be somewhere between 0.8 and 0.9. 
This means that P/M is twice as heavy as wood but, in 
practice, it is so much stronger that even if the plastic is 
only half as thick as the timber, which means that it will 
have the same weight, it will still be stronger than 
wood. 

To emphasize this point: 

If a P/M hull is to be the same weight as a wooden 
hull, the volume of material in the P/M hull can be only 
half that of the timber hull. This is accomplished by 
making the skin of the P/M hull only half the thickness 
of the skin of the timber hull. Even so the P/M hull will 
be stronger in all respects. Not only will the tensile 
strength of the P/M hull (both longitudinally and 
laterally) be greater than the timber hull but the impact 
strength of the P/M hull will also be greater than a 
timber hull of twice the thickness. 

The hulls of vessels shorter than 100 ft. (30.5 m.) 
are not highly stressed. On a 75 ft. (22.9 m.) trawler 
weighing 1 10 tons, the maximum stress on the extreme 
fibres at deck level or at the bottom of the skeg 
according to whether the vessel is in a hogging or a sagg- 
ing condition will not exceed 1,000 Ib./sq. in. (70 kg./ 
sq. cm.) if the thickness of the P/M deck and hull is 
approximately i in. (12.5 mm.) thick. 

The tensile strength of the P/M laminate is 15,000 lb./ 
sq. in. (1,050 kg./sq. cm.), so this gives an ample margin 
of safety. 

The only problem is to ensure that the hull is thick 
enough to withstand rough treatment in harbour where 
the vessel is likely to suffer from surging against 
the dock-side or against neighbouring vessels. This is 
more a problem of providing adequate frames and 
bulkheads. 



Rigidity 

The P/M laminate is very strong but it is also flexible. 
The secret of making a P/M hull so that it will be stronger 
than a timber hull of the same weight but equally rigid 
lies in stiffening the skin of the hull with hollow P/M 
"top-hat" transverse frames similar to the frames in a 
timber hull. 

This technique was developed and patented by the 
author's firm, see fig. 172. It consists of making a thin 
aluminium former of top-hat section over which a layer 
of P/M can be laid while in a wet condition. After the 
first layer has solidified a layer of uni-directional glass 
fibres, known as "rovings" are laid along the top of the 
frame so as to increase the tensile strength of the top. 
The frame is then covered with a further layer of P/M. 
By this system it is easy to make transverse frames for 
strengthening the main structure or horizontal frames for 
strengthening the bow or other special regions. 



ROVINGS 



LAMINATE OF 
2 OZ. MAT 




RIB FORMER 



SCRIM-* 
Fig. 172. Section through a top hat frame plastic construction 

Hollow skegs 

The skeg of a P/M hull is made in much the same way as 
the skeg of a steel hull. The skin of the hull is carried 
down to form a hollow skeg which is then reinforced by 
fitting P/M "diaphragms", or floors, in the way of the 
frames. These diaphragms are prefabricated the top 
face is turned over to form a right angle flange. The 
diaphragms are bonded into the skeg and then the 
transverse frames are carried across the top flanges of 
the diaphragms with the result that the diaphragms 
become part of the frames and the whole structure is 
therefore immensely strong and rigid as shown in 
fig. 173. 

Weight 

P/M hulls for power-driven boats, up to 30 ft. (9. 1 5 m.) in 
length, weigh approximately the same as equivalent 
wooden hulls. Larger power-driven hulls are lighter 
than equivalent wooden hulls, while still being of the 
same strength and equally rigid. 

It may be of interest to note that a P/M hull for a 
sailing vessel is a great deal lighter than the equivalent 
timber hull, because in a wooden hull there has to be a 
considerable weight of timber whose only function is to 
serve as a foundation to which planks may be fa&tened. 
For example, a P/M 40 to 50 ft. (12 to 15 m.) sailing 
hull will only be half the weight of the equivalent 
timber hull. 



[191] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 




CHAFING 1AR 



Fig, 173. Hallow polyesterlglass mat skeg % or keel, with the top of 
the floor diaphragm flanged to carry the top hat frames 



The horizontal and vertical faces of these tanks are 
prefabricated and then bonded into the hull before the 
frames are fitted. Large apertures are left in the top faces 
of the tanks so as to enable the tanks to be bonded 
internally as well as externally. These apertures are 
covered with conventional steel or aluminium cover 
plates with a neoprene gasket. The transverse frames of 
the hull are carried down to the top faces of the tanks 
and continued inside the tanks and up the vertical faces. 
The finished tank structure adds greatly to the strength 
and rigidity of the hull. 

For smaller craft, or when built-in fuel tanks are not 
required, it has been found that the most convenient 
form of engine foundation consists of a pair of } in. 
(19 mm.) marine plywood planks on edge running fore 
and aft. The bottom edge is bonded to the skin of the 
hull. Appropriate transverse members and anti-tripping 
brackets can be made either of marine plywood or P/M. 

An angle-iron engine girder is through-bolted to the 
top edge of the fore and aft plank to carry the engines. 



Tanks and engine foundations 

In large power vessels it is now usual to fit P/M fuel tanks 
and sometimes P/M water tanks. Diesel fuel tanks can be 
built into the engine compartment in such a manner as to 
serve as foundations for the engine girder. This is 
accomplished in a twin screw vessel by building a centre 
tank and two wing tanks. The space between the side 
of the centre tank, and the side of each wing tank, being 
such as will conveniently accommodate the engines. 

Steel or aluminium engine girders are then through- 
bolted to the sides of the tanks at an appropriate angle 
for the engines, and the engines are later bolted to these 
engine girders. A 56 ft. (17.1 m.) hull was designed to 
take two 250 h.p. light-weight diesel engines, weighing 
approximately 2 tons each, and to be mounted in this 
manner. 



TOP. HAT MAM 



UMWALt 




. /**. The interior of a 56 ft. (17.1 iw.) plastic huff thawing the 
integral fuel tanks and foundation* for the engine hearers 




175. Polyestei I glass mat hull with traditional wood deck. 
Note the covering board lodged on the gunwale 



This arrangement is cheap. It has been approved by 
Lloyd's and has proved exceedingly satisfactory. 

Tests have shown that a plywood plank mounted in this 
manner can take a thrust in excess of 6 tons/ft. (20 ton/m.) 
run of plank. 

The great advantage of both these arrangements, i.e. 
the engine secured to fuel tanks or to plywood founda- 
tions, is that no bolts pass through the hull below the 
waterlme and the engine load is transferred to the hull 
over a very wide area which helps to reduce vibration 
as shown in fig. 1 74. 

Decks 

All P/M hulls made by the author's firm incorporate a 
6 in. (150 mm.) vertical knuckle at the shecrline so as to 
provide a vertical face for the attachment of gunwales, 
fenders, decks, etc. 

It is easy to fit a wooden deck to a P/M hull An out- 
wale and an inwate or beam shelf are attached to the 
hull by through-fastening in the conventional manner as 
shown in fig. 1 75. Deck beams are fitted to the inwale or 



{192] 



NEW MATERIALS PLASTIC HULLS 



beam shelf in a conventional manner and planked. 
When wooden decks are required the top-hat frames are 
plugged with wood in the way of the knuckle so that the 
fastenings may be taken through the frames. 

For small boats it is easy to make a deck as a separate 
moulding with a vertical flange all around at the sheer- 
line designed to mate up with the vertical knuckle of the 
hull as shown in fig. 176. Frames are carried across the 
deck so as to match up with the transverse frames of the 
hull. After the deck has been dropped into place a 
timber outwale is fitted and secured to the hull by bolts 
which pass through the outwale, through the vertical 
deck flange, and through the knuckle of the hull. 

The joint between the knuckle and the underside of the 
deck is covered with a layer of P/M so as to make it 
waterproof. The deck frames and transverse frames of 
the hull are then joined by hollow knees. Thus the 
finished frames are continuous and are homogeneous 




Fig. } 76. Construction used in fining a polyester I glass mat deck 
to a polyester/glass mat hull 

with both the deck and the hull, which give great strength 
to the whole structure. 

There is an alternative system which is more suitable 
for large boats. A 6 in. (ISO mm.) wide horizontal flange 
facing inboard at the sheerline is moulded with the hull. 
This flange is recessed so as to take the thickness of the 
deck. The deck is made separately and can then be 
dropped into the recess of the horizontal flange to which 
it is both bolted and bonded. Again, the deck frames are 
bonded to the transverse frames with hollow knees. 

In order to provide a non-slip surface it is customary to 
face a deck mould with a synthetic rubber floor covering 
indented with a diamond pattern. The pattern is repro- 
duced on the P/M deck with excellent results. 



Marine plywood bulkheads are cheap and convenient. 
While the hull is still in its mould the plywood bulkheads 
are cut to shape and bonded into the hull with two layers 
of P/M applied on each side of the bulkheads at the 
junction with the hull in such a manner that the bonding 
extends for 2 in. (SO mm.) up both faces of the bulkhead 
and 2 in. (SO mm.) along the skin of the hull If the bulk- 
heads are installed while the hull is in the mould they can 
be fitted with great accuracy (see fig. 177). Moreover, 




Fig. 177. A 31 ft. (9.45 m.) plastic hull ready for delivery to the 

outfitting yard. It has a built-in spray chine, a P/M deck and the 

wooden bulkheads are installed 

the bulkheads serve to strengthen the hull and hold it 
rigid if the hull has to be transferred to some other shop, 
or delivered to some other yard for fitting out as shown 
in fig. 178. 

Tests show that the joint between a bulkhead and a 
hull which has been bonded by this method is at least 
twice as strong as the conventional method of securing 
bulkheads to wooden hulls. 

Bulkheads can be made of polyester mat but this is 
considerably more expensive than plywood. If steel or 
aluminium bulkheads are required a 4 in. (100 mm.) 
P/M transverse plate frame is moulded into the hull and 
the metal bulkheads are through-bolted to the frame. 

Deep plate frames of this type are heavier and more 
expensive to mould than hollow top-hat frames, but they 
can be far stronger and far more rigid. They were used 
in making the superstructure of a submarine which has 
lately completed all its sea trials and has proved equally 
strong but much cheaper, lighter, and more durable than 
an aluminium or steel superstructure. 




Fig. 178. A 56 ft. (17.1 m.) plastic hull awaiting delivery to an 
outfitting yard. Note the spray chine, the deep skeg and the bulk- 
heads installed ready Jar the outfitting yard to complete 



[193] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



P/M hulls and decks can be coloured to suit the owner's 
requirements. The colouring matter is ball-milled into 
the resin with conventional paint-making machinery. It 
is of great importance that the colouring matter should 
be evenly distributed through the resin so as to avoid 
the risk of shade variations. 

The coloured resin is generally only used for the skin 
of the hull and deck because it is wiser to use colourless 
resin for the subsequent layers of mat, since it is a great 
deal more easy to see and eliminate air bubbles in a 
laminate if colourless resin has been used. 

There is a tendency for customers to ask for pastel 
shades of blue and green, and though hulls can easily 
be made in these colours it may lead to difficulties if the 
hull ever has to be repaired because it is almost impossible 
to match these colours perfectly at a later date. For this 
reason it is wiser for hulls to be made either black or 
white. 

There is no need to protect a P/M hull with paint, 
but it is possible to change the colour of a hull by 
sanding down the surface of the hull in the ordinary way 
and painting it with a good quality paint. 

A P/M hull requires no maintenance. It is a homogeneous 
structure, therefore it cannot leak; it cannot corrode and 
it is not attacked by marine borers. 

Barnacles and algae will attach themselves to a P/M 
hull below the watertine in the same manner as a timber 
or metal hull, but they are far more easy to clean off. 
For example, there is no risk of damaging the hull by 
using a powerful detergent. 

A 54 ft (16.5 m.) hull, which has been working com- 
mercially at Aden for the past two years has never been 
painted with anti-fouling paint. It has been slipped 
every three months and cleaned off with a wooden 
scraper. The owners report that it can be cleaned in this 
way much more quickly than any other hull they have 
ever used, In spite of this, it is recommended that the 
underwater surface of hulls should be painted with an 
ordinary anti-fouling paint. 



One of the greatest advantages of P/M hulls is that they 
can so easily be repaired. If a P/M hull is damaged in a 
collision it can be repaired in about one-tenth of the 
time which would be taken to repair a wooden hull. If' 
a frame is damaged, there is no need to replace the frame 
as in a wooden hull, because the damaged portion of the 
P/M frame can be cut away and replaced. 
the procedure for repairing a P/M hull is simple: 
The damaged area is cut away with a hack-saw in such 
a manner as to produce a sBgbt bevel the wider part 
of the bevel on the outside of the hull Cellophane, 
backed T*feh any oonvrakmt fwrn <rf hardboard--or even 
a hanlboard with a waj^ surface 4s then secured to the 
outside of the hufl with adhesive tape and the repair is 



Repair kiU ate sullied whkhcoiisut of ilb. (0.225 kgO 



tins of resin, together with the appropriate quantities of 
activating chemicals in capsules. The first tin is opened, 
the chemicals added and stirred with a paint brush. The 
mixture will set within half an hour. The resin is applied 
with a paint brush from the inside of the hull to the 
cellophane surface covering the aperture. As soon as the 
area has been effectively covered with a film of resin, the 
tin wkh the remaining resin and the paint brush can be 
thrown away because they will solidify in half an hour. 

The second tin of resin is then opened and activated 
with chemicals. A piece of glass mat is cut to the right 
shape to fill the cavity and the resin is painted into the 
mat with the paint brush until it is effectively impreg- 
nated and bonded to the skin-coat. Again the tin with its 
remaining resin and the paint brush are discarded. This 
process is repeated until sufficient thickness has been built 
up. 

It will take half an hour to apply each layer, therefore, 
a hole in a 56 ft. (17.1 m.) hull, which is six layers thick, 
can be filled in about three hours. Even allowing for the 
time required to prepare the damaged area, and to sand 
off the outside after it has been filled, the whole job can 
generally be completed in an ordinary working day. 

Cost of hulls 

Cost is the only limit to the size of P/M hulls. Up to 
130 ft. (40 m.) in length the initial cost of P/M hulls is 
less than a wooden, aluminium or steel hull. The initial 
cost of a steel hull exceeding 130 ft. (40 m.) is likely to be 
less than a P/M hull because the raw materials of P/M 
are a great deal more expensive than steel. 

Where the shape of the hull does not involve much 
curvature, and in consequence little labour has to be 
spent in bending, steel has a clear advantage. However, 
with hulls of less than 130 ft. (40 m.) in length there is a 
great deal of curvature and much labour must be used to 
bend steel to shape. Moreover, the steel used for small 
vessels has to be so thin that it can easily rust through 
if the steel is thick enough to withstand rust, the hull will 
be heavy and expensive. 

P/M hulls cost the same or less than wooden hulk in 
spite of the fact that moulds are expensive, and in spite 
of the fact that the hulk for large power driven vessels 
must be properly stressed and must therefore be made in 
temperature controlled buildings, because it requires far 
less labour to build a P/M hull. 

The cost of a P/M hull less than 31 ft. (9.45 m.) in 
length will be less than the cost of a wooden hull provided 
that at least three hulk are required from the same 
mould. Between 30 and 50 ft. (9.15 and 15.2 m.) a 
P/M hull can compete with a wooden hull provided two 
hulls are required ftom the same mould. 

Above 50 ft. (IS nt) in length a P/M hull can compete 
with a wooden hull even if only one hull is required from 
a mould. 

For example, a 27 ft. (8.2 m,) hull is supplied for 
750 (*2,100); a 31 ft (9.45 m.) hull for 1,000 ($2,800); 
a 56 ft (17.1 m.) hull for 4,000 ($1 1,200); and a 75 ft. 
(22.8 m.) hull for 8,000 (122,400). 



NEW MATERIALS PLASTIC HULLS 



P/M hulls are dry, more durable, and far more easy to 
maintain than hulls made in any other material A single 
P/M hull for any vessel up to 130 ft. (40 m.) in length 
costs about the same as a wooden hull, but if several hulls 
are required from the same mould they will cost less than 
wooden hulls this is clearly of great importance for 
fishing fleets. 

P/M does not absorb any significant amount of 
moisture and therefore there is no risk of the material being 
contaminated by fish : moreover, it is a very good insulator ; 
consequently there is no risk of condensation in P/M hulls. 

There remains one further advantage which has not 
yet been exploited to any great extent. P/M can be 
moulded into shapes which could not be economically 
made in wood. For example, the author's firm mould a 



"spray chine" into all their hulls. A spray chine not only 
serves to break the bow wave and prevent it being blown 
over the deck in windy weather, but also adds greatly to 
the rigidity of the bow section without adding to the 
weight. It would be expensive to make a similar spray 
chine in wood or steel. 

Attention is drawn to the vertical knuckle which 
reduces the cost of fitting out and also adds to the 
strength. The author's firm have been able to introduce 
a generous and graceful flair into the bows of their hulls 
which again would not be possible in timber. It is believed 
that this is only scratching the surface of the possibilities 
and that there will soon be refinements of hull design 
which will, for example, permit greater speed for a given 
horsepower which will be easy to make in P/M but which 
would not be practical in other materials. 



[195 J 



PLASTIC CONSTRUCTION DISCUSSION 



Plastic construction 

MR. J-O. TRAUNG (FAO, Rapporteur): Hie only relevant 
paper on this subject was Gunner's describing a novel method 
of using a combination of plastic and plywood for a surf boat 
which is now under construction in India. For larger surfaces 
plywood is used, and for the comers, which are expensive to 
make in wooden construction, reinforced plastic is used. 

MR. . FEA (Italy): It was said at the first Fishing Boat 
Congress that, if it is true that many people consider factory 
ships to be the fishing craft of the future, it does not mean 
that smaller craft are going to lose their leading position 
throughout the world. The same speaker added that even 
when guided missiles and jets dominate outer space, mules 
and carts will still be used. 

Hardy in his valuable paper showed that of the thousands 
of craft throughout the world, all have elements in common, 
that is, there is a universal basis from which to start designing 
an efficient fishing boat. It can be asked if the many differ- 
ences that exist in fishing craft are due to specific needs, or 
are the result of tradition, which is often more of a handicap 
a noble handicap of course than an aid to progress. Every- 
one knows that the first steel ships were severely criticised by 
sailing experts; they said that the hull would become gravely 
and dangerously bent due to unequal heating by the sun on 
the side exposed to its heat for many hours, and the other in 
the shadow. We know now that the sun, fortunately, had 
some other preoccupation. 

Let us assume, therefore, that it is possible to reduce, on 
the basis of technical and experimental data, the large family 
of fishing boats. This immediately raises the possibility of 
prefabricating standard boats from the smallest to those of 
medium size. With existing lifting devices fat prefabricated 
components can be of considerable weight; but this must be 
carefully studied so as not to introduce many difficult 
problems of transportation. We need not look far for 
examples of prefabrication; the Germans and the Americans 
have built big ships, prefabricated hundreds of miles away 
from the sea. Up to a certain point we should forget that w 
are speaking of boats; the designer and the engineers or 
naval architects know perfectly well that they are designing a 
boat and they will act according to the needs; but the work- 
man who is riveting a steel plate is not so deeply interested 
in the ultimate end product, and does not necessarily require 
the boat to be built at the sea coast 

Prcfabrication means lower costs, due both to standardiza- 
tion and to lower labour costs. Assembly can be with bolts 
or by welding; for the smallest Graft there is no Assembly, 
because they can be delivered complete. 

With the above assumptions, die use of plastics for boat- 
building can be opportunely studied. It is not necessary now 
to detail the advantages of plastics ; it is sufficient to summarise 



their characteristics, which are: continuous and monobloc 
structure, low weight, non-rusting, smooth surface, perfectly 
watertight, elastic and at the same time strong, no maintenance 
costs, easily repairable. 

By plastics is meant polyester resins reinforced with fabric 
or fibre-glass, cold-lay. The construction of boats with 
thermoplastic under pressure cannot be considered because 
the cost of the large moulds and tools needed is prohibitive. 
But this method can be used for small components which are 
needed in large numbers, such as fish containers, net buoys 
and various fittings. 

Polyester resins can be perfectly married to the best 
insulating materials to obtain insulating panels for fish holds, 
refrigerator doors, etc. 

Generally speaking, plastics can be used for the following: 
lifeboats with air tanks, boats up to roughly 100 ft. (30 m.), 
partial or complete superstructures on bigger boats, insulating 
and protective sheets for holds, movable and transportable 
fish hold compartments, containers for fish storage. Another 
use is for wooden hulls in the form of protective internal and 
external skins. When applied for this purpose, suitable vents 
are provided in the plastic to allow the wood to transpire. 

Now would seem to be the time to formulate classification 
rules for plastic boats, with the co-operation of resin manu- 
facturers, naval architects and boatbuilders. The rules should 
start from the "equivalent resistance" point of view, and bear 
in mind all the positive qualities of polyester fibre-glass 
materials, such as the absence of corrosion, warping, decay, etc. 

Plastic is a lucky and enviable thing, because as it gets older 
it becomes stronger, without any particular care whereas for 
a man getting old is quite a disagreeable matter. 

Mr. Fea concluded his remarks by proposing that, seeing 
there is now the opportunity, with so many international 
specialists assembled, and knowing that there is a need to 
bring together, away from vested interests, all the sound 
and unbiased opinions and data on the use of plastics for the 
construction of fishing voats, their gear and fittings, it is 
proposed that FAO, which is the authoritative and appro- 
priate body, forms a permanent technical committee to study 
the aspects of plastics and their associated materials as they 
apply to fishing craft. It was further proposed that this 
committee, through FAO, collects information on plastics 
and disseminates it in the form of a periodical, or similar 
publication. 

MR, . McGRUBft (U.K.): He referred to de Laszlo't paper 
and mentioned that if the P/M was half the t of the equal 
weight of wood, then de Laszlo's conclusion was erroneous. 
The inertia of a section of 2t is 8 times that of t If P/M is 
only 2.5 times strong* (larch 4000, P/M 15,000) then the 
true relation should be: Wood*, P/M 2.5. If there is bending 
then the intensity of stress in 2t is twice that of t and the 



[196] 



NEW MATERIALS DISCUSSION 



relation under discussion becomes: Wood . P/M 1 For 
hull*. quality standard P/M ihoukl be compared with quality 
standard woods like teak, oak, Canadian rock elm, and 
Honduras mahogany. 

Ma. T. MITSUI (Japan): Polyester resin is an interesting new 
material, especially because of its great strength. It seems to 
bcimportantthatthcpoiywterfib^ 

For this reason the material should be good for panels, but 
there might be risks if it is used for parts where the fibrcgtass 
reinforcement is discontinued. The material may also not be 
successful for components subjected to great vibration or 
repeated stress, such as bottom fittings or engine beds. In 
order to maintain the strength, rigidity must be seriously 
considered. 

In Japan many ships are built partly of plastic resin. He 
would appreciate it if additional information about the 
methods to maintain rigidity in polyester resins would become 
available. 

MR. J. O. DE WIT (Netherlands): De Laszlo had given the 
thickness of the P/M hulls in relation to the length of the 
vessels. He wanted to know whether de Laszlo would inform 
him if the thicknesses had the approval of the classification 
societies or government organizations like the Ministry of 
Transport. 

The same question arose in regard to the composition of 
the hull. De Laszlo pointed out that he preferred using an 
outer skin layer and a number of inner layers of glass mat. He 
understood that de Laszlo had something against rovings in 
the hull. However he considered that in some parts of the 
hull it would be inevitable to use rovings where there were 
local stresses. 

He thought that the longitudinal strength of smaller P/M 
fishing vessels was of less importance that the resistance to 
local stresses. 

In comparing prices of steel and P/M hulls the question of 
life time of these vessels arose. He expected that the answer 
to this question would be that the steel hull has a longer life. 

DR. E. CROSIO (Italy): Everyone who is acquainted with the 
qualities of the new polyester-glass material is in favour of its 
being used more and more extensively in the construction of 
boats, even though their dimensions are limited for the present 
to lengths of from 100 to 130 ft. (30 to 40 m.). De Laszlo is 
to be congratulated on the brilliant results obtained by his 
company. 

De Laszlo mentioned the care that has to be taken in 
constructing the hull, on account of the effects resulting from 
temperature variations. In fact, one might ask why, in view 
of all the advantages of this new material, which should 
interest a good many shipbuilders, polyester-glass has so far 
been used only for the construction of hulk for military or 
pleasure boats. The use of polyester-glass depends on the 
possibility of effectively controlling the chemical phenomenon 
or hardening and the means available for doing so. The use 
of temperature-cxmtrolled catalysers is a tricky matter; the 
quantity to be incorporated depends on the surrounding 
temperature and cannot be determined by the craftsmen 
without die risk of serious difficulties. The presence of a 
chemist is necessary, whereas most small shipyards have 
none. 

These problems can be simplified by a new method of using 
polyester-glass which has already been used in Germany. 



chiti 



*es the glass fibres, cut from rovings at the time 
of use, with the polyester resin in a compressed-air spray. 
The mixture is then directed in the form of a jet against Hie 
surface to be lined. The layer thus obtained is then pressed 
by hand with appropriate rollers. The polyester resin is kept 
in two containers, one with the requited percentage of 
hardening, and the other with the catalyaor. Thus there is no 
risk of getting premature hardening, because the various 
components only react as they issue from the spray gun. 

The machine is capable of putting out about 310 Ib./hr. 
(140 kg./hr.) and the hardening of the layer takes about 
30min. The percentage of glass in the polyester-glass mixture 
is about 30 per cent, a very high figure for hand work, but it 
gives a very satisfactory mechanical resistance. It should also 
be noted that the cost price of the layers when this method 
is used is much lower than in the case of other methods, 
either because rovings, which are cheaper than glass mat, are 
used, or because of the saving on man power. 

Another possibility of using polyester-glass is in the lining 
of wooden hulls. In 1957 an Italian shipyard built a 40 ft. 
(12 m.) motor yacht, the hull of which was lined with a layer 
of polyester-glass. This Ligurian shipyard, which mass- 
produces such yachts, generally builds wooden frame hulls. 
The hulls are lined with planking consisting of a first layer 
of mahogany set diagonally and lined with cotton fabric 
impregnated with varnish and nailed by means of thick 
copper nails to the outer planking formed by parallel mahogany 
panels about 1 in. (30 mm.) thick. In the example mentioned, 
the outer planking and the cotton fabric were replaced by a 
single, continuous layer of polyester-glass, f in. (15 mm.) thick 
at the keel, and | in. (10 mm.) at the sides. These thicknesses 
were obtained by super-imposing several layers of glass mat. 
The results during two years* use have been excellent, and 
have confirmed the superior properties of polyester-glass. 
The use of the spray method for lining wooden hulls will open 
the way for small shipyards to turn the advantages of this new 
material to account, and will enable the shipyards already 
working in this field to reduce their cost price as a result of 
improved methods. 

Strength and cost 

MR. W. A. MACCALLUM (Canada): What was the strength of 
glass fibre reinforced plastic at the high temperature which 
might result in case of fire aboard ship? Would marine 
insurance rates be affected by the use of plastic? Would the 
reinforced plastic fishing vessel which could be built econom- 
ically be as good as the economically built wooden boat as 
far as resistance to impact is concerned? He suggested that 
in a cost analysis of wooden and plastic fishing boats costs of 
suitable fish rooms should be considered in each case. The 
plastic vessel would require an inner ceiling as well as Hie 
wooden vessel. Omission of a ceiling would expose the side 
and bottom of the vessel itself to abuse from implements, 
containers etc. Again on costs, Proskie's figures for Canadian 
wooden craft which include the cost of a deckhouse, complete 
crew's quarters, piping, 'galley, etc., are as follows: 

37 ft. (1 1 .3 m.) LOA longliner 645 ($1,800) 
45 ft. (13.7 m.) LOA ,, 4,200 ($1 1,70(9 
58 ft. (17.7 m.) LOA 5,600 (115,700) 
65.5 ft. (20 m.) LOA trawler 10,600 ($29,780) 

The figures given for plastic boats are difficult to compare 
with the Canadian figures since the former cover the cost of 
the shell only. Canadian cost figures for a complete 37 ft 
(1 1 .3 m.) wooden toogtiner compare favourably with those for 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



the 31 ft. (9.5 m.) plastic shell devoid of deckhouse* etc. It 
would be hdpftri if de Latzlo coukl provide cost figures for 
oomptoted vessels lest engine and screw, electronic equipment, 
winch and gallows and miscellaneous deck equipment. 

He suggested that Unit Bens as described in his own paper, 
mirfbt be a field in which the method of construction in plastic 
might be investigated. 

MR. L. CATASTA (Italy): Plastic hulls is an innovation of 
great importance, although in order to pay off the cost of the 
mould, it is necessary to use it to build many boats of 
identical shape and dimensions. Once one has selected a 
specific type of hull that has proved good in comparative 
model tests, It is possible to produce standardized hulls very 
quickly and at ever diminishing construction and operating 
coats. 

The insignificant water absorption of plastics is well known, 
and therefore the weight of the boat will not be increased, as 
happens with wooden hulls. Resin, reinforced with glass, 
makes a material of the best mechanical properties as 
compared with its specific weight. Its use makes it possible 
to build larger capacity, more durable, boats that offer better 
hygienic conditions, as well as effect a saving in power, 
because the hull was experimentally tested before the boat 
building was started. The problem is how to convince ship- 
owners to use standardized boats which, in addition to being 
seaworthy, are also cheap and good. 

Refrigerated holds are usually covered with insulation 
material (either cork, glass wool or sometimes sawdust, etc.), 
the inside being finished with wooden planking. Since they 
must be kept cool by ice or mechanical refrigeration, they are 
not ventilated. This means that there is a high degree of 
humidity permanently in the wooden planking and insulation 
material. 

Water absorption by plastic materials can be considered 
insignificant, and the suggestion has been made that expanding 
resins be used to cover the planks with reinforced polyesters. 
Expanding resins adhere strongly to the hull as soon as they 
are applied, so that there is no danger of ah* pockets being 
formed to vibrations or slipping of the planks. In addition, 
expanding resins absorb no water, since structurally they 
consist of closed cells that form when polymerization occurs. 
Hence, a reinforced polyester covered planking also 
guarantees that the stanchions and joints can be covered with 
a cement made of the same resin, thus obtaining a smooth 
surface that permits the draining off of the water formed 
from melting ice. 

However, the insulation material must be applied on the 
spot, and aa Italian firm which is conducting experiments on 
the use of plastics has built special machinery for the applica- 
tion of resins cm non-geometric surfaces, such as boat 
interiors. Even damage caused by violent Mows (which is. 
rare) can be quickly repaired by the boat's crew at minimum 
expense. In addition, die expanding resin can be used to 
prevent infiltration of water which occurs in any other type 
of boat, no matter how well it is caulked. 

The tow specific weight (between 0.02 and 0.04) makes it 
possible to use such a resin not only in the refrigerated hold, 
but also in many parts of fishing or cargo boats to ensure 
floataWky in case of emergency. Plastic materials, because of 
their lightness, cheapness, durability and deanlinra, offer 
obvious advantages eapecially to die large and important 
fl&eries industry. 

M*. H, B, STEBL (U.K.); His previous Department had 
!P/Mteticofiftnictkra of lifeboats. No speaker so 



far has mentioned robustness as a necessary quality in fishing 
boat scantlings and construction. It is so regarded for 
lifeboats. Another question regarding P/M boats was how 
long would they last? It was found that in the U.S. A., P/M 
boats had been operated for ten years and much experience 
was gained. A prototype lifeboat was hoisted in derricks and 
allowed to smash against a ship's side. It was then dropped 
into the water from a height of 23 ft. (7 m.). Little damage 
occurred. Tests on the strength of lifeboats was carried out 
in order to ascertain longitudinal and lateral deflections. 
Tests on lifeboats made after 12 months gave good results. 
More than 600 P/M lifeboats are now being used in British 
merchant ships. Reliable experience has accrued on construc- 
tional methods. Scantlings can readily be reinforced for hard 
sea work. He .concluded that there were good grounds for 
confidence in this material, at least for smaller classes of 
fishing boats. 

MR. J. VENUS (U.K.): One of the boats made by de Laszlo's 
firm has been sent to Aden. The hull was found to be perfect 
as it stood much knocking about and the owner was satisfied. 
This boat is 56 ft. (17 m.) long and fitted with aluminium 
girders. The boat is used as a harbour launch. 

MR. A. HUNTER (U.K.): He suggested the details of con- 
struction seem to have been rigidly modelled on orthodox 
construction and ignore many of the possibilities with P/M 
materials. The illustrations suggest an analogy with the early 
pratice when welding was introduced where riveted construc- 
tional design was rigidly followed. Sandwich P/M construc- 
tions had already been used in some applications. He was 
amazed at the statement about the cost of P/M hulls and how 
depending upon size, they could be comparable with wood 
construction even taking mould expenses into account. 
Prices for reinforced fibreglass lifeboats supplied to trawlers 
did not bear this out. 

Author's reply 

MR. P. D. DE LASZLO (U.K.) : As far as could be seen from the 
discussions, little opposition to this material was found. In 
regard to the tensile strength of the material the problem is to 
compare plastic and wood. A thousand tests have been made 
but the comparison is very difficult because the tensile 
strength of wood can vary as much as 100 per cent. It would be 
better to campare with steel. A plastic hull must be twice as 
thick as a steel hull. Comparison here is again difficult as an 
allowance is made in the thickness of steel plating for 
corrosion. 

The boats built so far were approved by Lloyds. Insulation 
value of fibre glass is good. There is little condensation as 
compared with steel. If glass mat is employed, fibres are 
arranged in all directions and no difficulty should arise 
regarding discontinuity of fibres when attached to the hull. 

The engine foundations can be made in a number of ways. 
A cheap way is to use marine plywood planks which can 
stand a pressure of 6 tons per foot run, which is alt that is 
necessary when considering the apparent loads and thrusts. 
Fatigue tests have revealed that glass reinforced plastic is six 
tones better than aluminium and vibrations occurring are 
also smaller than when aluminium is used. Regarding 
baking, this is no problem at all. Rovingi are advantageous. 

It is possible to increase the tensik strength up to 30,000 
Ib./sq. to. (2,100 kg./aq, cm.) by introducing glass fibre locally. 
This high tensile strength is normally not necessary as the 



NEW MATERIALS DISCUSSION 

maximum stresses occurring are only in the region of 15,000 The German machine described is an ingenious device. He 

lb./sq. in. (1,050 kg./sq. cm.). Frames of top hat section are would, however, be reluctant to use this machine. As regard* 

also used, the tensile strength of which is increased by rovings. covering a wooden hull with plastic material, the necessary 

As regards the life of a hull buih of P/M, this may be estimated thickness of the plastic it 0.06 in. (2 mm.) and not 0,4 in. 

to be 20 years. A steel hull may last for 50 to 100 years but, (10 mm.) as sometimes suggested. Wooden plankings with a 

after 30 years, it may have corroded so much that the boat plastic covering have, however, a greater tendency to rot. 

cannot be used. The conclusion is that, as far as small hulls The cost of construction of the hull is competitive with wood, 

are concerned, plastic hull is good. The plastic hulls must be His firm is now making 40 hulls for the U.S.A. as this has 

made in temperature controlled rooms. A good plastic been found to be cheaper than wooden hulls obtainable in the 

material can only be made by qualified chemists. U.S.A. 



[199] 



THE CARE OF THE CATCH 

by 
G. A, REAY and J. M. SHEW AN 

The main features of fish yp* iu gi largely caused by marine bacteria, and main factors in controlling it on trawlers, especially 
distant-water ones, are described ana discussed. 

Temperature is the most important single factor affecting spoilage and therefore in its control. With minimum delay the catch must 
be thoroughly drilled (typically iced) and kept so until landed. Delay should not exceed the kg phase of the spoiling bacteria, which, for 
example, 5 only about 2 to 3 hours at 59F (15C), a possible air temperature even in northern fisheries. Gutting and washing on deck 
inevitably dekys stowage of the catch: but washing tanks now common on British distant-water vessels and the recently tested South African 
washing flume considerably reduce demy and warming up and permit a more even flow of fish into the hold and a steadier rate of stowage in 
ice. Fornx>trapkioverallccolmgofthecatc^ An average satisfactory 

ratio of ice to fish might be 1:3. In British distant-water vessels the ratio is now nearly 1:1. 

T*mfrlnffHl refrigerating grids, sometimes installed, have not the advantage once assumed and can best be used only on the way to 
the fishing grounds to cool the nshroom and its fittings and to keep the ice crisp. 

Care and cleanliness are the other important factors influencing quality. Fish, easily damaged by rough handling and even moderate 
pressure, become softer and flabbier and more spoiled when piled too deep on deck, when tramped on in deck operations, when stowed below 
between shelves more than 18 to 30 in. (45 to 75cm.) apart, etc. 

The bacterial load of the unused ice increases during the voyage from 10 s to 10* per ml. to 10* to 10 7 per ml. as it lies in the ice 
pounds, the increase comprising mainly fish-spoiling types. Washed fish can thus rapidly regain their original bacterial loads. The 
effectiveness of antibiotic ices may partly be due to supression of bacterial multiplication in the ice itself. 

Fishroom walk, fittings and shelves should be kept as clean as possible. Wood cannot be kept bacterially clean. Metal surfaces 
are much mote easily cleaned and do not carry sub-surface infections. There is no clear evidence, however, that the bulk of the fish in 
well-cleaned metal holds is kept in improved condition. 

LES SOINS A APPORTER AUX POISSONS PECHES 

Les auteurs d6crivent et examinent de facon critique ks prtncipales caractiristiques de 1'ahiration du poisson, causee en grande 
partie par ks bact&ies marines, et ks principaux facteurs servant a hitter contre 1'alttaation a bord des chahitiers, en particulicr ceux pdchent 
dans les eaux ioignes. 

La temperature est k facteur simple k plus important dans 1'alteration et par consequent dans la lutte contre cette alteration. Dans 
un minimum de temps, k pftche doit etre refrokik avec soin (gto&akment par mise on glace) et maintenue ainsi jusqu'au dibarquement. 
Ce minimum de temps ne doit pas d^asser k phase de ktence des bacteries de k putrefaction qui est, par exempk, d'environ 2 a 3 hres 
jeukment a 59F (15C), temperature possible de 1'air, m*me dans les ptehes septentrionaks. L'arrimage de la pechc est in6vitabkment 
retard* par l^visceratton et k kvage sur k pont, mais les bacs de kvage, qui sont maintenant communs a bord de na vires britanniques pftchant 
dans les eaux Hoignees, et I'auge de kvasje sud-africaine essayed reoemment, r6duisent considirablemcnt cette duree ainsi que k i&hauffement 
et permettent un feoukment phis rtgulicr des poissons dans k cale et une vitesse plus consume de Fan-image dans k glace. Pour un 
refroktisaement general plus rapide des captures, k glaces doit etre bien mekngee aux poissons, &ant en contact avec chacun d'eux. Une 
proportion moycnnc de la glace par rapport au poisson, qui soit satisfaisante, pourrait etre 1 :3. Dans les navires britanniques pechant dans 
les eaux eloignees, k rapport eat actuefiement pfus voisin de 1 il . 

Les serpentins itttiffaants, parfois install** sous k pont, ne prescntent pas les a vantages que Ton avait supposes et il est preferable 
de ks utilise? seukment pendant k route vers ks lieux de pechc pour rcfroidir U cale a poissom ct ses annc?^ ct consen^r U glace craquante. 

Le soin et k ptoprete 1 sont les autres facteurs important* ayant une influence sur k qualite. Les poissons sont fadlement endomma06s 
per une manutentkm bnitak et memc des pressions moderes, et quand ils gisent en couches trop epaisses sur le pont, quand ils sont pie* tines 
pendant k travail sur k pont, quand ils sont amines en cak entre des planches s6parees de plus de 18 a 30 pouces (45 a 75 cm.), etc., Us 
deviennent plus mous, plus flasques et phis alteres qu f tls ne dcvraicnt. 

La charge bact6riefine augmente dans k mace pendant k transport de 10* a 1C 1 par ml. a W a 10 7 par ml. quand les poissons sont 
mis dans des ^tageres avec de k gkce, Taugmentauon portant surtout sur ks especes putr6fiant k poisson. Les poissons kvls peuvent ainsi 
rapidetnent regagner leurs charfcs bact^riennes originates. L'efficaciti des glaces aux antibiotiques pout 6tre due partiellement a k suppression 
de k muHiplkation bac^rienne dans k gkce eOe-m&ne. 

Les parois, ks Atagfcres et ks planches de k cak a poisson doivent etre maintenues ausst propres que possible. Le bob ne peut pas 



^tre maintenu bact^riolqgiquement propre. Let surfaces metalliques, qui ne portent pas d'infection au^dessous de la surface, sont beaucoup 
plus facite* a nettoyer. IT n'est pas certain, oependant v que f ensemble des poissons se maintienne en meiUeur eiat dans des catos m6taUiques 
oien nettoyees. 



EL CUIDADO DE LA CAPTURA 



Se docribeo y rxaminan las caracteristicas principales de la altegadon del pcacado,causadasen gran partc por tes bacterias marioas, 
itoras flEias Jooportafitei de la hicha contra la afteracion a borao en we arrastreros, paitlccUatinente kM de gran aitura. 
LatemperttuimeselCKAorquemasinlluyeenkdctorioi^^ La captura debe ser enfriada 

raenteenhielo)skipAlidactetiem^ Bsto mfatmo de tiempo up debe exceder la 

i toteate de las bacterias deteriorativas, la que es, por cjempk), de solamente 2 a 3 horas a 5^F (15*O. temperatura del aire que se 
aentraaunenlaspesqueriastepteotrkmales. U est^ de la captun la retaida bieviubleomto k ev^^ 
con los tanques de kvado, ya muy comunes en los anaatreros brittoicos de 0ran akura v coo h* ^firft%OT onsayados PsoliitiUimomo tn 
So4*fHca,se reduce cnftttiera^^ 



FISH HOLDS CARE OF THE CATCH 

mas coottajKto lie flHy*tK i * < iffnftitffrtA 40 hielo. Pant u& cnffiamieato enecal mat raptdo de la captura, d hiitlh* dt^Tf fttur mvy i r _ _ _, 

cipcfcadoyeocontactocoiicadauno. Una rotation media latttfactoria de hick) y peecado podria ser de 1 :3. En lot barcos britAnicos de 
gran ahura la retacion e aproxima mis a 1 :1. 

Lot serpentine* refrigerante* <pe algunas voces ae instalaban en las cubiertas no lienen taa ventaja* que ae lupufkron una vez y e* 
preeribto empleaiios aotomente en d viaje de ida a lot caiaderot para enfiriar la bodefa de peecado y MM anexot y para cootervar el biek> 
crujieme. 

El cuidado y to limpieza son los otros factoret de importancia que influyen en to calidad. 1 peacado se magulla con ftdlidad si no 
K trata con cuidado y aun tl te aomete a Preston moderada, debtdo a to cual ae pone muy btondo y ae eatropca mas de k> ncceaario cuando 
ae apiton rouchot en to cubterta, cuando ton pitotcados durantc las toborea normaiea y cuando ae ahnaoenan en eatantca con tefmracioiie* 
de mis de 18 a 30pi4. (45 a 75 cm.) t etc. 

Durante el viaje, to carga bacteriana en el hielo aumento de 10* a 10* por ml. a 10* a 10 7 DOT ml. cuando el peacado etta en loi 
compartimicmoa, contapoiidiepdo cati todo el aumento a las especies que detenofmn el peacado. Uebido a dlo, el peacado tovado puede 
rccupcrmr rapidamente sus cargas bacterianas originalea. La eficada de los hielos con antibiotioos puede debene parcialmente a to aupraion 
de to multiplicacton bactertona en d hklo. 

Las paredea, d material, y las ptonchaa de to bodega de peacado deben nnanteneiie eacnipuloaaniente limpiot. La madera nose puede 
mantener libre de bacterias. Las auperAdea metalicaa ae limpian mucbo mas facilmente y no son portadoras de infeociones debajo de to 
supcrftcie. Sin embargo, no hay pruebas concretas de que to masa del peacado ae conserve major en bodegas metalicas muy limpias. 



THE function of a fishing vessel is to catch fish and 
to preserve and land the catch in as fresh a 
condition as possible. That function must clearly 
influence vessel design not only in relation to catching 
operations but also to those of handling and storing the 
catch. The purpose is to indicate the main principles of 
good practice, so far as they seem to have been established 
in talcing care of the fish. 

Whilst foods in general are perishable and delicate 
cargo, fish is exceptionally so; and the designers of fishing 
vessels are concerned with the supremely important first 
and often long link in the chain that joins catching to 
final consumption of the commodity. As far as the 
quality of the product is concerned, what is done on the 
fishing vessel cannot later be undone or offset. 

The paper deals mainly with chilling preservation in 
trawlers at sea typically by stowage in crushed ice 
of demersal or "white" fish. 

WHY AND HOW FISH GO BAD 

The freshly-caught fish goes bad, i.e., suffers undesirable 
and finally unacceptable changes, particularly in odour, 
flavour and appearance, mainly through bacterial de- 
composition. In addition, enzymes naturally present in 
the flesh, organs, etc., of the fish play a still inadequately 
assessed part in deterioration either directly or by pro- 
viding the bacteria with readily assimilable nutrients. 
Enzymes are, of course, involved in the first spectacular 
change occurring after death, rigor mortis, and this must 
have largely passed off before bacterial action can develop 
in the flesh, 

In the very earliest stage of storage in ice it seems 
probable that bacteria take little part in the gradual loss 
of the characteristic delicate odour and flavour of very 
fresh fish. The chief causes appear to be leaching out of 
soluble flavorous substances by the ice water and 
enzymic activity. In the case of fatty fish, such as those 
of the herring, pilchard, mackerel and salmon groups, 
the flesh of which may contain about 2 to 25 per cent of 
oil, depending upon species and seasonal and biological 
factors, oxidation of the oil can contribute significantly 
to spoilage. Rth oil* being of the unsaturated, "drying" 
remdily combine with atmospheric oxygen, with the 



assistance of catalysts in the flesh, to give rise finally to- 
rancid odours and flavours. In comparison, very lean 
fish, such as cod, haddock and whiting, which contain 
considerably less than 1 per cent, of fatty material in the 
flesh, do not noticeably exhibit this type of deterioration. 
In the very earliest stage of storage, before bacterial 
multiplication has set in, oxidation possibly contributes 
to the loss of very fresh aroma in both lean and fatty fish. 

In the normal, healthy, newly-caught fish, the flesh and 
organs are completely free from bacteria (Reay and 
Shewan, 1949). The external surface, however, harbours 
large numbers and so does the gut unless, as happens at 
certain times, the fish is not feeding. The bacteria on the 
outside of the dead fish multiply in the slime covering the 
skin and gills, which is a good nutrient substance, pro- 
ducing stale and finally foul odours as welt as rendering 
the initially clear slime opaque and finally discoloured. 
As a result, the flesh becomes tainted through absorption 
of the bacterial products and is also itself invaded by the 
beleaguering bacteria, which proceed to multiply in it. 

More often than not there is food in the gut of the 
newly-caught fish in process of being broken down by the 
powerful enzymes of the digestive juices. The gut wall* 
which is resistant to attack in the live fish, readily 
succumbs after death to the digestive action of the 
enzymes, which can then proceed to penetrate into 
neighbouring organs and regions of the flesh, digesting, 
softening or "jellying" them. Moreover, the bacteria 
that are normally associated with the food in the gut can 
now readily penetrate into the same sites and multiply 
there, although there is no clear evidence that the par- 
ticular types found in the gut produce the noisome pro- 
ducts characteristic of spoilage. When much food it 
present, the speed with which the gut wall can break 
down and the belly walls be jellied and even perforated 
by the digestive enzymes is astonishingly great, even when 
the fish are chilled in ice. From this it will be apparent 
why, if possible, fish should be gutted and washed at 
sea soon after catching. For the most part, this is the 
custom in the trawl, seine and line fisheries for demersal 
or "white" fish; but it is never done in the fisheries for 
pelagic species, such as herring and pilchard, which are 
small fish usually caught in great numbers. 



[201] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



The bacteria responsible for spoiling fish on the fishing 
vessel, and apparently during subsequent distribution, 
are marine types. They arc of the psychrophilic so- 
caUed cold-loving variety, which exhibits most rapid 
mcreasc in population in the region of 68 to 75 F 
(20* to 24 C). In comparison, most pathogenic bacteria 
producing disease in hot-blooded animals have much 
higher optimum temperatures, mostly about 99F (37 C). 
All varieties of bacteria build up populations more 
slowly the lower the temperature is below the optimum; 
but whilst the growth of almost all pathogens is com- 
pletely inhibited at melting ice temperature, the marine 
bacteria continue, although slowly, to multiply under 
such chill conditions. Some remain sluggishly active, 
even in frozen fish, down to a temperature of about 
19.5 F (7 C). There is considerable evidence to show 
that in lowering the temperature into the region around 
32'F (0C) the inhibitive effect of cooling accelerates 
markedly with each successive degree. AH this means 
that spoilage can still proceed in ice-chilled fish, even 
before the fish is landed, at a rate and to an extent of the 
highest significance for commercial fish handling. Main- 
tenance of the lowest possible temperature short of 
freezing is indeed far the most important requirement for 
retaining the quality of the catch. Apart from tempera- 
ture and time, the other important factors affecting 
preservation are care and cleanliness in handling, which 
will be discussed later. 

Table 45 (Cutting, Eddie, Reay and Shewan, 1950) 
shows the average course of spoilage during three weeks 
of carefully gutted and washed newly caught cod and 
haddocks kept in plenty of ice. Four fairly recognizable 
phases of spoilage, as observed sensorily, are shown side 
by side with indications of the corresponding increases 
in bacterial numbers in the flesh and in three volatile 
bases produced mainly by bacteria. The relevance of 
these data to distant-water white fisheries will be obvious. 



The average round voyage for such British trawlers is 
about 20 days, involving some 5 days for return to port 
from the grounds. Landings on the average comprise 
fish stored in ice for periods ranging from 5 to IS days, 
i.e., fish in phases II and III. This illustrates the order of 
the limitations of ice as a preservative under the best 
possible normal conditions, i.e., without adding chemical 
preservatives or antibiotics. Vessels often have to return 
to port incompletely filled because of the spoilage of the 
early caught fish. 

Table 45 applies specifically to gadoid, i.e., cod-like, 
species which account for the bulk of the demersal 
catches in the North Pacific, North Atlantic and Arctic 
areas. There are, of course, variations in the rate of 
spoilage under standard conditions dependent on intrinsic 
factors such as size, species, biological condition, fishing 
ground and season, the effects of which are far from being 
thoroughly evaluated. It seems clear, however, that other 
things being equal, large fish spoil somewhat more slowly 
than small fish; and flat fish generally keep better than 
gadoids. 

It is possible that the bacteria on tropical or sub- 
tropical fish may be somewhat more susceptible to 
control by chilling than those found on fish whose 
habitat is in much colder waters and that in consequence 
fish kept well iced immediately after catching may take 
somewhat longer to become inedible. Some evidence is 
accumulating to this effect. 



Control of spoilage 

Spoilage being mainly due to bacterial activity, control 
mainly consists in combatting this. To do so means, in 
effect, reducing the bacterial population on the fish 
before stowing it in the hold and preventing subsequent 
increase whether through multiplication, for which 
temperature is the most important factor, or through 
additions arising from contamination. 



TABLE 45 



Diagram staring side by ride tbe orgmnoteptic, cberaioil and bacteriological changes in buttocks, 
canMy gntted and imbed and stowed in plenty of toe 



Storage time in ice in days: 



I stowed in plenty < 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 



ORGANOLBFIIC CHANGES . 


Phatel 
No marked spoilage 


Phase II 
First definite signs of 
pdilage; softer flesh, sta- 
tar appearance, strength- 
ening of odour 


Phase HI 
Definite stale ap- 
pearance and odour 
and soft flesh 


4 , > 

Phase IV 
Rapid deterioration from 
stateness to putridity 



Storage time in ice in days 
CHEMICAL CHANGES 



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 











Triraethykinine increases nmkfiy 



I- 



Ammonia increases rapidly 



Stooge time in ice in days 



! 2 3 4 5 t 6 7 8 9 10 11 12 13 14 IS 16 17 18 19 20 



FISH HOLDS CARE OF THE CATCH 



TEMPERATURE CONTROL 



The task of first importance in treating the catch is to 
chill it thoroughly as soon as possible and to keep it 
chilled until landing. It is, of course, impossible to 
express the effect of temperature on the rate of spoilage 
in a simple and, at the same time, accurate manner; 
but from bacteriological, chemical and taste panel data 
and "averaging out" over the period that elapses before 
the fish reaches the point of inedibility (taken at Torry 
Research Station as 15 days in ice), fish such as cod and 
haddock spoil about two and a half times as fast at 
40F (4.5C) and about five and a half times as fast at 
50F (10C) as at 32F (0C). 

The white fish catch by trawlers is gutted and washed 
before being put below for sorting and stowage in ice; 
and there are no special arrangements on deck for cooling 
the fish. There is thus some delay before cooling can be 
effected but it should be reduced to the unavoidable 
minimum. Bacteria exhibit a "lag phase" before they 
multiply and, in theory, cooling should be commenced 
before this phase is passed. The duration of the "lag 
phase" for marine bacteria at 32F (0C) is about three 
or four days and at 68 F (20C) possibly not more than 
two or three hours. 

Just after World War II, when Arctic catches were 
much heavier than now and when a haul might be 
brought aboard before all the previous ones had been 
put below, delays on deck were observed to be at times 
as much as 12 to 24 hr, (Rep. Food Invest. Bd., Depart- 
ment of Scientific and Industrial Research (DSIR), 
1948, 1949). The air temperature in northern latitudes 
can rise to 50F (10C) or even higher in summer, and it 
was found that the bacterial load offish exposed on deck 
at 45F (7.2C) for 18 hr. increased 10 to 100 times. 
The quality of the fish at landing IS days later corre- 
sponded to fish iced very soon after catching after 
17 days. (Cutting, Eddie, Reay and Shewan, 1950). 
Canadian workers (Castell, MacCallum and Power, 1950) 
have reported air temperatures on vessels on Eastern 
Canadian grounds of 37 to 70F (3 to 21C) from May 
to July, and that exposure on deck for more than two 
hours during the warmer weather is decidedly detri- 
mental to the fish. The Fishing Industry Research 
Institute, Cape Town (Cooper and Rousseau, 1955) cites 
temperatures of stockfish as high as 81F (27.2C) after 
99 min. on deck, the temperature of the fish at catching 
being about 59F (15C). Arrangements introduced 
since the war for mechanically washing the gutted fish 
and directing them by chute into the fishroom have very 
considerably contributed to di&inishing delays on deck 
(see also page 241). 



;sapptyof ice 

Gutted fish are typically stowed in the hold with ice on 
shelves, or in boxes in some of the smaller vessels. Ice 
must be sufficient in amount to oool the fish as quickly as 
possible to jiut above the temperature at which freezing 



can begin, say 30*F (-1.2C) t for most "white" fish, 
and, in addition, to keep the fish cooled until landing. 

It is of the utmost importance to mix the ice well with 
the fish for rapid cooling so that ice is in contact with each 
fish. It is surprising how little this is appreciated by many 
in the fish industry. Fish is, to use the canners' termino- 
logy, a solid non-convecting pack through which heat 
transfer is much slower than is often supposed. A rough 
practical rule would be that fish more than, say, 2 to 3 in. 
(50 to 75 mm.) thick should always be stowed in layers 
not more than one fish deep, between upper and lower 
layers of ice. 

Although theoretically one part of ice is required to 
cool seven parts of fish from about 55 to 32F (13 to 
0C), such cooling is impossible in practice. The ad- 
mixture of ice with fish cannot be made sufficiently 
intimate; moreover, some ice is consumed in cooling 
shelves, fittings, etc., although this is relatively small in 
amount. MacCallum (1955) points out that while it is 
impossible to give rules for the amount of ice necessary 
for chilling the fish and the fittings completely, good 
results are obtained by mixing ice intimately with the 
fish in a ratio by weight of 1 to 3.8. The Torry Research 
Station has recommended a ratio of 1 to 3 (Cutting, 
Eddie, Reay and Shewan, 1953). 

Heat leaks 

Provision has also to be made for absorption of heat 
entering the fishroom from outside so that this does not 
denude any part of the catch and heat it up. Holds vary 
greatly as regards heat inleak, depending upon the 
absence or presence of insulation and mechanical 
refrigeration, whilst external climatic conditions vary 
widely. It is not sufficiently realized that heat inleak 
from the sea through the sides of the ship is almost 
as important as that through the deckhead. Obviously 
ice must be deployed in the right amounts and positions 
to ensure that at the end of a voyage there will still be 
ice in contact with linings and bulkheads and at the top 
of the stowage. 

The correct deployment and requirement of ice can 
only be found out from experience with each particular 
vessel. Obviously the most difficult conditions are 
encountered in uninsulated ships; and satisfactory 
deployment of ice is probably easiest of all where the 
fishroom is simply insulated, or where insulation is 
combined with jacket cooling. Here temperature condi- 
tions in the hold should be at their most uniform and 
permit something like a standard stowage and icing 
procedure to be practised in any ship, some allowance 
being made for climatic variations. 

The use of deckhead refrigerating grids, which have 
been installed in insulated holds in some instances, has 
been found in practice to have less advantage than 
expected. Deckhead grids, in which the refrigerant is 
usually well below the temperature of melting ice, oool 
the air immediately under the deckhead. As the coded 
air falls all the air in the fishroom will gradually be 
cooled and it will cool any part of the room to which it 



[203] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 

circulate. The chief uses of dccfchcad grids are thus 
witiy to cool the empty fishroom, to keep the ice in 



crisp, easily-handled condition and to cool all shelves 
and fittings before the fish is stowed (Cutting, Eddie, 
Reay and Shewan, 1953). 

Grids can also keep the air cooled above "shelved" 
fish, i.e. in British practice, fish merely laid on a bed of 
ice with no more than a sprinkling of ice on top. At the 
top of the pounds containing "bulked" fish, i.e. fish 
completely stowed in ice, the pipes can merely absorb 
heat coming from the deckhead and can have no effect 
on the temperature of any fish more than a few inches 
down in the stowage, whether the linings, etc. are metal 
or not There is some danger of superficial drying of the 
"shelved" fish and also of freezing some of the fish, 
whether "shelved" or "bulked". This latter can readily 
happen since unavoidable local variations in air tempera- 
ture during stowing are bound to occur in the air above 
the pounds and accurate thermostatic control from one 
single point, which is attempted, is not really possible. 
Frosting and defrosting of the coils also contribute 
practical problems. On balance, it seems clear that 
deckhead grids offer no proved advantage in preserving 
the cargo as compared with the use of plenty of ice. The 
jacketted hold represents a much more sensible approach 
to this whole problem even than extended grids over tfie 
sides and bulkheads. However, unless the jacket is 
hermetically sealed off from the fishroom, desiccation 
of "shelved" fish may still occur. 



Afedtadcal refrigeration 

Quite apart from the dangers of slow and partial freezing 
of some of the fish in a mechanically refrigerated fish- 
room, some experimental results (Rep. Food Invest. 
Bd., DSIR, 1948; Ofterdinger, 1950) pose the question 
whether the quality of fish is not better if the air tempera- 
ture in the hold is kept somewhat above 32F (0C) or 
if, more generally, the heat flow into the ice apart from 
that coming from the fish itself is such as to permit a 
steady melting throughout the voyage. Some data 
obtained at Torry Research Station (Rep. Food Invest. 
Bd., DSIR, 1954, 1955) with individual boxes of iced 
fish at different ambient air temperature, ranging from 
32 to 53F (0 to 12C), showed that in the case of the 
highest ambient temperature the fish reached inedibility 
some 1 to 2 days later than the fish kept at 32F (0C), 
Chemical and bacteriological evidence supported this. 
It is doubtful if this effect, which presumably is due to 
removal of bacteria and leaching out of their products, 
would be completely reproduced in a fully stowed pound 
of fish. However, it seems clear that, to preserve good 
external appearance ("bloom") the surface of the fish 
should remain moist. This is another reason for mixing 
ice well with the fish and for specifying that mechanical 
refrigeration should be operated so that the lower limit 
of air temperature anywhere in the hold is, say 33F 
(0.6 Q C), rather than, say, 31.5F(-0.6CX the freeing 
point of the fish. 



Hea* 

Another feature relevant to temperature control that 
might repay further investigation is the production of 
heat in stowage by the growing bacterial population on 
the fish and by possible tissue oxidation, Calorimetric 
experiments (Rep. Food Invest. Bd., DSIR, 1954) with 
chopped haddock muscle in ice have indicated a con- 
siderable production of heat, calculated as being equiva- 
lent to the melting of 25 tons of ice on a North Atlantic 
trawler trip, but the figure might be of quite different 
order for whole fish under conditions of commercial 
stowage. 

Total amount of ice needed 

MacCallum's (1955) calculated requirements of total ice 
to total catch (100 tons in the medium-sized Canadian 
trawlers considered) range from 1 :1.5 for an uninsulated 
hold with wooden linings and boards poorly preserved 
to 1:3 for an insulated, wholly refrigerated metal 
surfaced hold. Ratios for actual usage in 1953 to 54 
are quoted by MacCallum for a group of insulated 
wooden-lined vessels (1:3) and for another group of 
insulated, refrigerated wooden-lined vessels (1 : 2.25). 
The calculated requirement in the first case is 1:2, so 
that the amount used in practice is actually less. The 
calculated figure given for an insulated, metal lined 
(not wooden-lined) vessel is 1 : 3, this amount being satis- 
factory in practice. Requirements will, of course, vary 
with the size of the ship, the size of the catch, the duration 
of the voyage and the climatic conditions. 

In British practice, vessels of 165 to 185 ft. (50 to 
56 m.) making distant-water trips of 20 days on an 
average, take to sea about 90 to 110 tons of ice for 
catches which range from 75 to 200 tons the average 
in 1956 was about 1 10 tons. Of the ice loaded, perhaps 
70 to 80 tons is used for an average catch. These quanti- 
ties ate ample to meet the exigencies of adequate tempera- 
ture control, and generally this seems to be satisfactorily 
achieved. A large number of observations in recent years 
show that the temperature of distant-water fish, mainly 
cod, at landing ranges from 31 to 42F (-0.6 to 5.6C), 
half the values laying between. 

Mechanical refrigeration by itself is certainly not a 
satisfactory method of chilling fish and the only possible 
alternative to the use of ke seems to be stowage in chilled 
sea water. This has been developed so far for certain 
fisheries and species, mainly in Canada (Harrison and 
Roach, 1955). 

CARE AND CLEANLINESS IN HANDLING 



Fish is very easily damaged by rough handling and even 
moderate pressure. Care should therefore be taken to 
avoid this. Pressure, such as may occur in bringing very 
large bags of fish on deck, in lying several feet deep in the 
dock ponds for some hours in being tramped upon during 
deck operations, gutting; etc, and at the unstowing in 
port, ami in being stortd in the hold with ice to dqrths of 



|2W] 



FIftH HOLDS CARE OF THE CATCH 



more than 2 or 3 ft. (0.6 to 0*9 at) for days on end, 
mutts in the fish being softer and flabbier than they need 
otherwise be. Sudden, sharp pressure, as in being 
tramped upon, has been shown (Castell, MacCallum 
and Power, 1950) to result in abrasion of the skin and 
subdermal tissue cells, which become more readily 
penetrated by the surface bacteria with resulting en- 
hanced spoilage readily distinguished after a week in 
ice. Bruising of freshly caught live fish may cause Moody 
discolouration of the flesh involving loss of yield if 
subsequent trimming has to be resorted to. The con- 
tinuous pressure bearing on the fish when stowed in the 
hold results in the loss of juice and hence of weight to a 
notable extent (Cutting, 1951). For example, on trips of 
18 to 24 days an average of 7 per cent, of the weight 
(and about 3 per cent, of the protein) of a catch of cod 
and haddock was lost. The staler the fish and the deeper 
the bulk of fish and ice, the greater was the loss. After 
18 days at the bottom of a mass 4 to 5 ft. (1.2 to 1.5 m.) 
deep, the weight loss was 14 per cent, as against 3 per 
cent, at the top. At the other extreme fish stowed in 
single layers in shallow boxes, 8 in. (203 mm.) deep, 
gained 1 per cent, on the average, whilst the average loss 
was 3 per cent, for fish stowed between shelves 1 ft. 
(0.3 m.) apart. 

In bulk stowage of fish and ice, the shelves should be 
placed at vertical intervals of not more than 18 to 30 in. 
(457 to 762 mm.). The space between shelves should be 
filled completely with fish and ice, but care should be 
taken that the fish is not subject to the weight of the shelf 
above. In other words, the shelves should be leaning on 
the rest-angles or battens. 

Deterioration through pressure in stowage is seen at 
its worst in the case of oily, "feedy" herrings. This is 
being increasingly recognized on British vessels and 
boxes are coming into much more general use. Ice also 
is beginning to be used, but there is still some reluctance 
to do so even on larger vessels. This may be a survival 
from the days when salt curing was the chief outlet for 
the catch, it being held that iced herrings made a poor 
cure. 



Cutting or piercing the flesh of fish, such as by knives in 
gutting and by hooks at unloading, opens the way for 
bacterial entry and local spoilage and often discolouration. 

Some thought is being given to new methods of 
storage, e.g. large containers, which would be filled at sea 
with fish and ice, and lifted from the hold at the port. 
Besides saving labour in discharging, this would avoid 
the damage to the fish that occurs as the result of using 
hooks, ice shovels and throwing baskets into the hold. It 
would still be necessary to sort the fish on shore before 
exposure for sale. These new methods of stowage might 
require larger hatch openings, and even a single con- 
tinuous hatch in the biggest trawlers. The adoption of 
the submarine manhole within the hatch proper for 
access at sea would seem to make this feasible. 

From first principles and in relation to preserving the 



quality of the catch, cleanliness in handling is mainly 
concerned, on the one hand, with reducing the population 
of bacteria on the fish as it corns on board and, on the 
other, with preventing the addition of bacteria from the 
surfaces with which the fish comes into contact on the 
ship. The presumptive need for cleanliness in relation 
to quality is well recognized by the British industry. 
Further care in hygiene in various ways might not in it* 
totality produce the enhanced quality of catch that might 
be expected. The scientific evidence is somewhat con- 
fused as yet laboratory results not always being repro- 
ducible in commercial practice. But any relaxation of 
hygiene in handling and stowage would be most likely 
to result in lowered quality. 

Mud from sea floor 

Besides the bacteria naturally on the fish in the sea, 
others get on to it during trawling on the sea floor, 
especially if muddy. Indeed, considerable quantities of 
mud can be brought on deck along with the fish. It is 
presumed from its general type that the mud flora 
includes fish spoilers. There is also evidence (Liicke and 
Schwartz, 1937) that, as a result of pressure in the hoisted 
trawl bag, intestinal contents along with their bacteria 
are extruded and spread amongst the catch, although 
apparently this flora is not predominantly of a fish- 
spoiling character. 

Despite the reservation made above regarding the 
effectiveness of still more cleanly handling than is prac- 
tised, it is commonsense to recommend that decks and 
deck pond boards should be thoroughly hosed down with 
seawater between hauls. 

Gutting 

The fish should be carefully gutted as soon as possible 
after hauling, all viscera being removed without cutting 
into the flesh. Ideally, the guts should not be allowed to 
fall on ungutted or gutted fish. However, guts are often 
dropped on the ungutted fish, which become progres- 
sively dirtier, the guts being finally washed overboard. 
Layout of the deck ponds can be made to assist cleanli- 
ness here. 

Washing fish 

The next process is washing the gutted fish, if only to 
remove gross dirt, blood and slime. This, ideally, should 
in some way be done with running water. When washing 
was done properly, e.g. by hosing fish individually, it 
was shown (Georgala, 1957) that the surface bacterial 
load on cod (10 1 - 1 to 10* per sq. cm.) was reduced by 
some 80 to 97 per cent. The fish thus carefully washed 
reached inedibility some two days later than unwashed 
fish, when kept in bacteriologically clean ice. Washing 
of this sort is practically impossible on trawlers catching 
fish at normal rates and it would not take much less than 
the percentage reduction in bacterial load just indicated 
to wipe out the enhanced preservation. Until recent 
years fish on British trawlers were washed by playing 
the hose upon heaps of fish stirred by foot or sometimes 
by hosing the fish in baskets given a rotary shaking. 



{2G5J 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



Where there was room, fish have also been cleaned by 
passing them into a partially dammed deck pond fed 
by a hose. 

In recent years a special washing tank has come 
increasingly into use. As they are gutted the fish are 
thrown into this tank, which is raised well above the 
deck and is fed with seawater through a jet on each side. 
The jets produce a swirl and the fish emerging from the 
partially dammed end of the tank, looking well washed 
and free from obvious blood and slime, are led by chute 
to the stowage pounds below. This washer has certainly 
introduced a new element of order into the deck pro- 
cedure, the fish passing continuously from the deck to 
the fish hold. On an average the fish is stowed in ice 
much sooner than previously, in fact very soon after 
gutting. This is a notable improvement and the fisher- 
men are enthusiastic about it. South African workers 
(Cooper and Rousseau, 1955) have adopted a flume 
washing apparatus, fig. 201, in which the fish are brought 
from gutting to delivery by chute into the fishroom with 
more than 50 per cent, reduction in the average maximum 
time of exposure of the fish on deck and considerable 
lowering of the fish temperature. 

There are no data, so far as is known, concerning the 
greater bacteriological efficiency of these washers as 
compared with normal washing practice. There is, 
moreover, lack of agreement amongst investigators 
about the advantage in preservation to be gained by 
washing followed by normal stowage on trawlers. 
Ludorff and Kreuzcr (1956) found after washing with 
greater care than might be possible in practice that the 
fish kept better after 16 days 9 stowage than those treated 
by the crew in the normal way. Castell, MacCallum and 
Power (1950), on the other hand, could find no advantage 
in washing with extra care but their fish was stowed for 
no longer than 6 to 7 days* In a number of experiments 
on a British distant-water trawler (Rep. Food Invest. Bd., 
DS1R, 1954 and 1955) no difference was found between 
unwashed and very carefully washed fish stowed in 
boxes with the ship's ice after 10 to 15 days 9 storage, 
most of which occurred on shore after landing* This 
result appears to conflict with that quoted above, viz. 
that some two days' advantage could be gained. How- 
ever, the explanation may well lie in the fact that the ice 
was bacteriologteally dean as compared with the ship's 
ice, which, in the experiment, was taken near the end 
of the fishing period. 

The bacteriological condition of the ice as a separate 
factor has been found by both Canadian (Castell, 
MacCalhim and Power, 1950) and British worker* (Rep. 
Food Invest Bd, DSIR, 1955) to be of considerable 
importance. Fresh crushed artificial joe as delivered to 
the fishing vessel contains relatively few bacteria, 10 1 to 
1 per g* and these are mostly not considered to be fish 
spotting types. White stowed in the ice pounds in the 
bold for the voyage the tee becomes more and more 
contaminated with bacteria, presumably from the ice 



pound walls and division boards, which have often 
previously served as fish pound boards or shelves, and 
from contact with shovels used for icing the fish* and 
with the fishermen's boots. All these infections 
carry nutriment with them which will support further 
growth. 

On a typical distant-water Arctic trip from the Humber, 
the counts for samples of the trawler's ice on reaching the 
fishing grounds some four days out of port were about 
10* per g., whilst at the end of the fishing and on return 
to port the figures were about 10* per g. The Canadians 
(Castell, MacCallum and Power, 1950) report, counts of 
the order of 10 7 per g. Several samples of unused ice 
from trawlers returning to Aberdeen have also had 
counts of this order. The flora of the unused ice after a 
voyage was found predominantly to resemble the flora 
of fish. When very well washed codlings were stowed in 
clean boxes with factory ice they became inedible some 
five days later than similar codlings stored with unused 
ice from a fishing vessel. However, too little work has 
yet been done to assess satisfactorily the significance of 
the part played by ice in increasing the spoilage of the 
catch under commercial conditions. 

Contact with hold walls 

Fish can be contaminated not only from contact with the 
trawler's ice but also from direct contact with dirty 
shelves, walls and linings. Most of these, however, are 
still wooden and shortly after being painted, varnished 
with shellac or coated with various surface sealers, 
become porous and water-sodden and harbour beneath 
the surface multitudes of bacteria. It is generally agreed 
that so far it is impossible in any simple, practicable 
manner to sterilize such wooden fittings. It is not sur- 
prising, therefore, that it has not proved possible in 
practice to demonstrate convincingly that fish stowed 
in wooden holds, cleaned by practicable methods, such 
as washing with detergents and disinfectants, are very 
much better in keeping quality than where cleaning has 
been less careful. Indeed, it is perhaps improbable that 
contamination from the wooden fittings can affect the 
quality offish other than those in close contact with them. 
This, however, could perhaps amount to only a few per 
cent, of the catch in British distant-water trawlers, which 
use a high ratio of ice to fish (e.g. 1:1.5) and usually put 
extra ice between the fish and the walls of the fish hold. 
Some Canadian workers in recent years (MacCallum, 
1955; and McLean and Castell, 1956) illustrate how fish 
can be spoiled through contact with wooden walls and 
division boards and shelves. It was found that fish 
pressing closely on the wood during a voyage can fre- 
quently develop a particularly foul, sulphide-like odour, 
reminiscent of bilge water, which permeates part or at 
times the whole of the flesh, resulting in what is known to 
the trade as a "bilgy" fish. The cause was shown to be 
spoilage by facultative anaerobic bacteria resident in the 
wet, worn wood. This type of spoilage has alto been 
recognized cm British trawlers (Burgess and Spencer, 
1958), To avoid it, the Canadians recommend that the 



{206] 



FISH HOLDS CARE OF THE CATCH 



fish be kept away from the wood by means of ample 
local icing or by heavy wire netting screens. 

MacCallum (1955) recommends the use of a consider- 
able amount of ice to make certain that the fish does not 
come into contact with the walls of the pen or pounds. 
As much ice by weight as 22 per cent, of the total catch 
is suggested in the case of holds with poorly preserved 
wooden linings and boards and about 8 per cent, when 
the holds are metal-lined. 

Metal-lined holds and metal shelves can be much more 
effectively cleaned and sterilized than wood and, of 
course, do not carry sub-surface infections; but there is 
apparently no published evidence to show that, apart 
from the less frequent occurence of "bilgy" fish, the 
bulk of the catch is kept in improved conditions. On the 
commonsense ground, however, of maintaining a proper 
regard for care throughout the whole treatment of a 
foodstuff, good cleaning of fish holds and their fittings to 
prevent the accumulation of gross dirt must be strongly 
recommended. 

As it is easier to clean portable boards than fixtures, 
vertical pounds divisions should, wherever possible, be 
built up from boards and stanchions, the fixed wings 
remaining only at the sides of the ship, where they are 
necessary to avoid the use of boards of special sizes and 
shapes. In the same way it is better to have separate, 
portable rest-angles to carry the horizontal shelves, 
rather than rest-angles fixed to stanchions or battens 
fixed to special boards. These features also make it 
easier to work in the fishroom both when stowing the 
fish and discharging it (Eddie and Waterman, 1958). 

Although too little work has yet been done on the 



subject and sampling methods require closer investiga- 
tion, direct contact with contaminated ice especially later 
in the voyage, would seem at present to be a source of 
spoilage. It is difficult to see how this could be entirely 
eliminated, even in a metal-fitted hold kept thoroughly 
clean, except by incorporating a bactericidal or bacterio- 
static substance in the ice. 

Work in many parts of the world has shown that at 
least two antibiotics, chlor-tetracycline and oxy-tetra- 
cycline, when incorporated in the ice can afford about a 
week's extra preservation beyond the normal point of 
inedibility (She wan, 1958). Part at least of the effect of 
this treatment is no doubt to be accounted for by counter- 
acting the spoiling load that builds up on the ice. 

Anaerobic spoilage takes place only when the fish is 
directly in contact with smooth surfaces, especially 
infected wood, and can be avoided in the manner 
described. So long as this is done, it is the opinion of 
many practical men in the British industry that exclusion 
of as much air as possible from the stowage gives the 
best results, and considerable trouble is taken to avoid 
air spaces when bulk stowing fish, but whether in fact 
the result obtained is due to the exclusion of oxygen (in 
the air) or to some other factor, such as the prevention 
of warming-up by inflowing warm air, has not been 
examined scientifically. In any case trade practice is 
inconsistent as "shelfing" is advocated by the same 
people. 



The work described in this paper was carried out as pan of the 
programme of the Food Investigation Organisation of the Depart- 
ment of Scientific and Industrial Research. 



[207] 



THE FISH ROOM ENGINEERING AND ARCHITECTURE 

by 
W. A. MAcCALLUM 

The naval architect can serve the fishing industry better if he understands fish preservation. Much "know-how'* is at hand and the 
time to apply the results of engineering progress and technological advancement is when the vessel is in the planning stage. This paper 
i and dimensions of holds, compartments and containers for various fisheries and types or vessels; and improvt 



concerns desirable shapes and dimensions of holds, <mpartmentt and containers for various fisheries and types or vessels; and improvements 
of old and development of new features for fish storage. 

Particular importance is attached to the arrangement of fish rooms for the iced storage of "wet'* fish, salted fish, and fish room 
construction for handling either iced "wet" fish or fish refrigerated in sea water. Both fixed and movable elements are considered for 
transverse partitions in fish rooms. Integral transverse partitions and ceiling linings of two designs in aluminium alloy are cited. Practical 
steps to cut coats and reduce difficulties in placing boards in divisions, transverse partitions and shelves in trawlers are outlined and details of 
construction are shown. Inadequate planning offish room layouts in small wooden trawlers and longliners is described. 

The features of some paints, woods, plastics, glass fibre reinforced plastics, galvanized steel and aluminium alloys are noted. Methods 
of preventing die catch from touching the woodwork are discussed. Tables show the types, characteristics, and gauges of aluminium 
alloys used. 

The design and use of pen boards of wood and aluminium alloys components are discussed. Aspects of ventilation in wooden ships 
are discussed; and so is the undecked small fish carrier. A similar analysis is made of small decked boats, longliners, trawlers and cutters. 

LES CALES A POISSON-- TECHNIQUE ET ARCHITECTURE 

L'architecte naval peut rendre dc meilleurs services a 1'industrie des pecbes s'il connalt la preservation du poisson. Les connaissances 
acquises sont importantes, et c'est au moment dc retabltssement des plans du navire qu'il convient de mettre en application ks resultats 
des progres mfcaniques et de Tavaaoement des techniques. Les informations examinees concernent: ks formes et dimensions desirables des 
caks, compartimenU et recipients pour let diverses peches et les divers types de na vires; les ameliorations des caracteristiques anciennes et la 
mise au point de nouvelles caracteristiques pour 1'entreposage du poisson. 

On attache une importance particuliere a la disposition des caks & poisson pour 1'entreposage en glace du poisson frais, du poisson 
said et 4 la construction des cales 4 poisson devant recevoir soil k poisson frais en glace, soil le poisson refrigere dans Teau de mer. Les 
dements Axes et amovibtes sont constderes pour ks separations transversaks dans ks caks a poisson. Les separations transversaks integrates 
et deux types de doubiage du plafond en auiage d'aluminium sont cites. L'auteur indique des moyens pratiques pour diminuer ks depenscs 
et reduire les difficult^ quand on place ks planches dans ks divisions, les separations transversaks et ks etageres a bord des chalutkrs, et il 
donne cks details de construction. II decrit aussi des projets de disposition de cak & poisson ne convenant pas a bord de petits chalutkrs et 
palangrier* de bois. 

Les caracteristiqucs de quelques peintures, bois, matieres plastiques, matieres plastiques renforcees de fibre de verre, ackr galvanise 
et alliages d'aluminium sont indiquees. L'auteur examine ks methodes pour empecher k poisson de toucher k bois. Des tableaux indiquent 
ks types caracteristiques et epaisseun des alliages d'alurninium utilises. 

Le dessin et Templet de planches d'etageres de bois et d'alliages d'aluminium sont commentes. L'auteur examine ks divers aspects 
de la ventilation 4 bord des navires de bois et aussi des petits transports de poisson non pomes. II donne une analyse semblabk des petits 
navires pontes, des palangriers, des chahitiers et des cotres. 

LA BODEGA DE PESCADO INGENIERIA Y ARQU1TECTURA 

& aiqtutecto fuval puede prestar seiv^^ 

Existe mucha information sobre d particular y el momcnto de aplicar los resultados de los adclantos <k la inenlorfa y de la tecftka e$ cuando 
dtarcoestatodaviaenproyecto. 1^ infornuu:i6n qiie se disorte esta re^ 

compartimjentos y wdpicntc* para difmntes clases de pe** y tipos de barco, mejora de las caracteristic** viejas del ahnaoenamknto de 
pescado y forraulacion de otras ituevat. 

Seda< 



la const rucciondeUbwic^ para manip^^ Se estudian tot ekmentos ityos 

ymovilpan^separackroestramversalei Scmeiickjtxanpartickmestwir^ersalesint^ 

ocdoproyectosbasadosenden^ko<kakd6iidealumu^^ Se mencionan medidas practicas para redudr los cottos y las diffciiltadc* de 



, _. _ 

p*nasenla*divi*ioi>MyKdandatoflydc^^ 
describcn lot ddbctos k la madem paralapescaalarrastrey alpalangre. 

Se mnckman ctm^rislicas <k algimv 

ac*ro galvanizado y akactones de aluminio. Se discutcn los procedimicntos qoe existen para evfcar quo d pescado este en contacto con 
kmaderiL Se dan tabias de tot tipo^ caracristicas t y eyesores cte las ak^^nes dc atominJoT 

Seexamii^laajaitn^nycitvkockpaiw Sc 

i aspectos <fe la vcntiladon en barcos do madea. Se dtscute d barco transportador de pncado sin cubierta v se haoo un aitilisis 



1208] 



FISH HOLDS ENGINEERING AND ARCHITECTURE 



A N important improvement would be realized if at 
fJL the time a vessel is in the planning stage, fish 
JL jL room location, shape, construction and fitting out 
were given the same careful consideration as hull form, 
safety at sea and main engines. Thus boats should be 
designed with fish handling and fish preservation charac- 
teristics very much in mind. In many details the naval 
architect should be able to improve present facilities for 
handling and storing the catch. 

The naval architect must co-operate with the fisheries 
engineer, the owner, and the builder in connection with 
the installation of sea-water chilling tanks, visceral and 
liver tanks, and changes from conventional practice in 
the relative positions of fuel tanks and stowed fish. He 
must also be a guide as to the effects these developments 
will have on stability, safety, and other operating 
characteristics of the fishing boat. 

The first seven sections deal in the main with larger 
boats, and the last two sections with small fishing 
craft, with the exception that ventilation, in the last 
section, applies to wooden vessels of all sizes. 

LARGE FISHING BOATS 

The ideal storage room is the rectangular prism because 
it is easiest and cheapest to fit out and easiest to use. 
Hence it is of great advantage to have the fish room as 
uniform and as fully-shaped as possible from aft to 
forward. Barker suggests that a true rectangular paral- 
lelepiped be considered in diesel trawlers without double 
bottoms. He proposes that fuel be carried in wing tanks 
on each side of the fish room. For a given cubic capacity 
between engine room and forward bulkheads the fish 
room would be longer and narrower and of approxi- 
mately the same volume as when transverse tanks are 
used. The design would: 

Provide less "lost" space where boxed fish are stowed 

Give complete interchangeability of all fish room 
boards used for bulk stowage 

Reduce costs and increase efficiency of space utiliza- 
tion if jacketed Unit Pen type construction 
(MacCallum, 1954a, 19SSa) for bulk stowage were 
desired 

Give the same advantages with regard to installation 
of seawater chilling tanks 

Lead to shorter pens for bulk stowing, thus reducing 
the work of the icer and probably increasing efficiency 
of icing 

Result in more constant trim 

The proposals are worthy of careful consideration by 
naval architects. 

Obstructions in fish holds sometimes reduce the 
effectiveness of space available and increase costs when 
metal tanks, Unit Pens and metal linings are fitted. The 
architect should strive to provide an uncluttered fish 
storagespace. 



Typical fish and ice weights and states of stowage to 
help in design calculations are shown in table 46. 

INSULATION 
Typical coosUerations relating to the we of kMobtkra 

Whether or not to insulate depends on how many of the 
factors in table 47 apply. These and possibly other factors 
may have different significance depending upon which 
pan of the fish room is considered, viz., end bulkheads, 
deckhcad or ship's ceiling. Special weight should be 
given to factors that are important in the area or condi- 
tions under consideration. The remarks opposite items 
10 and 1 1 indicate the majority point of view, at least in 
some countries. The cost of insulation alone can seldom 
be balanced against the cost of refrigeration as is done in 
land storage. The insulation protective covering cost and 
possibly the cost of ventilating the vessel's structure 
behind the insulation must also be considered. 

Table 47 indicates doubt concerning installing insula- 
tion on the fish room ceiling. But insulation is needed if 
too little ice is used, which otherwise results in poor 
quality fish. 

Time in storage is of great importance in determining 
quality, and is dependent upon: 

Distance to the fishing grounds and vessel speed 

Rate of catching and stowing 

Carrying capacity of the fishing craft 

Because of the relationship, varying though it may be, 
between vessel size and time of fish in storage, it is 
sometimes possible to by-pass certain factors and to 
associate the use of insulation with a particular type of 
boat of a certain size. Thus, Norwegian Fresh Fish 
Regulations, 1952 state that the end bulkheads in the 
fish room of wooden seiners 50 to 60 ft. (15 to 18 m.) 
long should be insulated, and in Japan insulation is 
applied on the ceilings, end bulkheads and deckheads of 
all steel and wooden boats over SO GT. It is estimated by 
H. C. Hanson that in Southern California 100 per cent, 
of the tuna boats, both steel and wood, 90 ft. (27 m.) 
and more in length are insulated, and 25 per cent, of 
those between 60 and 90 ft. (18 and 27 m.) in length are 
similarly fitted out. 

Quite apart from its contribution to fish-saving, 
insulation, when used effectively, contributes to better 
fish room operation. The saving in man-hours with 
insulation is worthwhile when icing the fish. It also 
saves fatigue and this results in more careful icing. 

Judicious use of insulation can result in a gain in space 
for fish storage. Examples are illustrated in fig. 180, 181 
and 1 82 and discussed later. 

Insulation rtqdremeats fa sled ' 

As pointed out by Smith (1951) the calculation of heat 
flow through a wall of insulating material with intruding 
steel members is difficult and complicated. A stiffener 
adjacent to the lining will contribute to a substantial 
area which will be nearly as warm as the outside of the 
insulation. Isotherms do not run parallel to the outside 



1209] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



TABLE 46 
Typfcal fisfe wdght art 



Weight 



State 


lb.lcu.fi. 


kg. leu. m. 


References 


m Ugpllliil co* (in pre-rigor and rigor state, shallow bulked 


47 to 52 


753 to 833 


MacCaltom, 1958 


b@) Gtto*co*(laidin*uifterowsoniceoni^^ 








unrt of i*/ volume offish hott, British trawlers) . 


15.5 


248 


Eddie and Waterman, 1958(a) 


b(ii) Gotfe* cad (in pro-rigor and rigor state, shallow bulked 








without ice) 


45 


721 


MacCallum, 1958 


c(i) Qatss* ce* flfnP ha**ock iandod (shallow bulking in ice in ratio 








of ice to fish by weight 1:1 to 2 per unit of net volume of fish 








hold (Skagen, Denmark) 


31 to 37 


497 to 593 


Bramsnaes, 1958(a) 


c(ii) Gfrttc* co* mi HiMsBfr hade* (shallow bulking in ice in ratio 








of fee to fish by weight 1 :2, per unit of net volume of fish hold, 








British trawlers) ........ 


35 


561 


Eddie and Waterman, 1958(a) 




(4.0 cu. ft./ 
10 stone kit) 






cQii) Gtftto* CQ*M* WUtock lands* (shallow bulking in ice in ratio 








of tee to fish by weight 1:2.5, per unitof net volume of fish hold 


41 


657 


Bramsnaes, 1958(a) 










removed from fee and shallow bulked without fee) 
d Bex** fiat (per unit of ^-055 volume offish hold, British seiner) 


55 

31 


881 

497 


MacCallum, 1958 
Eddie and Waterman, 1958(a) 


e$ Grabs* lee at 32*F (O'CX unpacked as at loading into the 








fishing boat 1 . . . 


35 


561 


MacCallum, 1958 


e(ii) Crabs* lee m* 32*F <0C), tending to solidify after prolonged 








storage, in the fishing boat, awaiting use .... 
f Flake lee at 32 F(0O, unpacked, as at loading into the fishing 


41 


657 


MacCallum and Da wson, 1959 


boat 1 


26.5 


425 


MacCallum, 1958 



Results of sieve analysis of crushed ice at 32'F (0C) as at loading 
into the fishing boat 

Per cent, by weight of ice 
retained on sieve 

5.9 
64.8 

{ in. (19 mm.) mesh 80.1 

in. (9.5 mm.) mesh 97.5 



Sieve No. 

1} in. (38 mm.) mesh 
in. (25 mm.) mesh 
19 mm.) mesh 
9.5 mm.) mesh 



1 



Remark! 

Results of sieve analysis of flake ice at 32 F (0C) as at loading 
into the fishing boat 

Per cent, by weight of ice 
Sieve No. retained on sieve 

1 i in. (38 mm.) mesh 0.0 

1 in. (25 mm.) mesh 41.8 

{in. (19 mm.) mesh 75.2 

in. (9.5 mm.) mesh 93.2 

3 

Net volume is less than gross volume by pen divisions, shelves, 

stanchions, etc. In bulk stowage, the weight of fish per unit gross 

volume of fish holds may be considered to be 10 per cent, less than 

the weight per unit net volume 



Typical 



TABLE 47 
rdatiaf to the we of taralalioa on the ceiling of i 



Factors 
\. Material used in construction of vessel 

2. Air and water temperature 

3. Available space in fish room in relation to 
catch, 

4. Effect of me of insulation in causing 
deterimticm of ti* structure 

5* Duration of fishing trip. 

6. Speck* and type of fish landed. 

7. Fish handung to the area. 



ityofice : 



A /^ mm ^ii j m+ **f it^ mimr^mif^ft aJ n n mt ^ff 

TJ> \MmaSaun oc MB recjuirea ana oott or 

10. S^d availability of suitable insulating 

11. Cost and availability of suitable pro- 



Case considered 
Wood 
62*F fl.7-O ( AT30F or 16.7*Q. See 

44 Influence on fish hold carrying capacity" 

in text and fig. 181. 
A maximum qf 2 in. (51 mm.) loss of space 

(including space for ice) against existing 

ceiling of uninsulated boat is original goaf 
Reasonable, though not guaranteed, pro- 

visions made to prevent dry rot. 
Seven days, 
Atlantic groundftth (cod, haddock, etc.) 

landed for ftesn and frozen fish trade. 
Relatively low-priced fish requiring high cafe 

of stowing. 
Ice readily available at low price. 



*? to obtain, butmto relatively 
high compared to price of fiati* 



itlicoovred to price of 



Insulation 

Recommended Not recommended 
X 



X 

(see fig. 181) 

X 

X 

X " 

X 



X 
X 



C210J 



FISH HOLDS ENGINEERING AND ARCHITECTURE 




00 
LOW Of 



10 t.o o *.o eo .o ro ro o tao no 

AC* AT OCMLMO "WOHKt (MCASUMMIMTt 0,0, M lUUtTMTIOM A AND ft, M lUMTBATttN 0, 



. 180. Space lost diagram for the ship's side of a wooden longtiner 



and inside wall surfaces and the conductance of any 
section of unit length is larger than the sum of the 
conductances of each section comprising the unit. The 
equivalent insulation depth is in some cases less than half 
that of the overall insulation depth of the structure, due 
to the stiffcners alone and without considering the adverse 
effect of grounds, chocks, or fastenings. 

Where the ship's wall, bulkhead or deckhead is built 
to offer the same resistance to heat flow as the con- 
ventional cold storage wall, having a chosen depth of 
insulation, the actual thickness of insulation required on 
the fishing boat may be determined as follows : 

An average value of the desired* thermal transmission 
factor, U is put in the standard formulaf 



U=- 



1 



ft f fc ' t ' " * Ir" 

l| IQ ivi K| K n 

and then the values applicable to fishing boats for f and 
fi for the surface conditions and of k!, k . . . k n for 
materials and insulations are substituted. As required, 
the conductivity coefficient k used for the insulation may 
be adjusted to take care of water absorption, effect of 
convection currents in the wall, imperfect workmanship, 
etc. The equation is solved for the appropriate symbol 
L which refers to the net thickness of insulation when the 
walls are considered to be without frames, stiffeners, etc. 
This thickness will be denoted as L, the effective 
thickness of insulation. 

The amount of adjustment to be made to k is 
purely arbitrary. For rockwool and corkboard an 



*The effect *t varioui values of U on hold 
the qiumtJttot of Ice which should be 
tte following 2nd and 3rd tub-iections. 

t See Appendix 1 for explanation of formula. 



' and 
is'corisidered in 



increase over manufacturers' ratings of 25 to 50 per cent, 
appears to be warranted for low temperature storages 
(Lorentzen and Brendeng, 1955; Merlin, 1955). A 
similar increase would appear to be justified for applica- 
tions in some wet fish holds where wetting of insulation 
by absorption is prevalent. An increase in k could also 
take care of the effect of grounds between metal stiffeners 
and fish hold linings. 

The overall insulation depth, always greater than 
U where ship's members intrude into the material and 
hence also greater than the depth of frames, may be 
determined through the use of available data, in the case 
of steel ships, obtained from the electric analogue 
method of accounting for the effect of frame and beam 
profiles (Smith, 1951). 

In specifying insulation for steel ships, flanges of 
beams and stiffeners should be separated from the 
lining by unbroken layers of insulation, as shown by 
fig. 182, illustration B. 

The Gregson System, found in such trawlers as the 
Bay Ella, formerly Cayton Bay (Birmabright Ltd., 1951), 
is one practical solution to the problem of insulating a 
wall into which steel stiffeners intrude. 



Insolation requirements in wooden vessels 

The standard formula (Appendix 1) is used for deter- 
mining heat flow through the- wall of an insulated 
wooden vessel and it is assumed that the conductance of 
any unit is the gum of the conductances of each section 
comprising the unit. The area of wooden frames and 
stiffeners represents a fairly large percentage of the wall 
structure. Thus, for ease of installation, etc,, insulation 
is often omitted from between-frame spaces and is 
placed in uninterrupted layers over the ship's 
ceiling. 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 

coct cot s 



AT etft.Mtt-MOMCftlMCAM*tlMT t,O, IN ICUT*TION A AND 0, M lUMIHATlON .MO*) 




. 757. S/wre tot/ diagram far the ship's side of a wooden trawler 



Iritatnce of insulation on fish hold carrying capacity 

In deciding upon the thickness of insulation Li OF 
<fig. 182) and Li (fig. 180, 181), it is helpful to recognize 
the point at which fish hold carrying capacity is being 
sacrificed. Typical instances for the sides of wooden 
longlincrs and wooden and steel trawlers are considered 
in fig. 180, 181, and 182. A study of bulkheads and 
deckhcads can be made in a similar manner provided 
that in deckhcads the effect of transfer of heat from the 
inner lining to the ice by convection be considered. 
The following assumptions have been made in con- 
nection with calculations used in making the diagrams. 

Thermal conductivity of the insulation 0.33 BTU 
in./hr./sq. ft/F (0,00011 36 cal. cm./sec./sq. cm./'C). 

The inner lining covering the insulation is 1 in. 
(25 mm.) pine for both steel and wooden vessels. The 
insulating effect of a covering or coating is very small and 
has not been considered. 

Zero resistance (l/fi=-0) to heat flow exists in all cases 
between the inner linings and the ice with which these 
are in contact. 



The ship's ceiling next to the frames of the wooden 
longlincr is 1 in. (25 mm.), both non-insulated and 
insulated; 1J in. (37 mm.) in the wooden trawler; and 
\\ in. (37 mm.) with a \ in. (12 mm.) air space for the 
uninsulated steel trawler. 

Insulation is continuous between and over frames of 
the insulated steel vessel. 

The U-value for the non-insulated wall in the steel 
vessel (fig. 182, illustration A) is computed as if the wall 
were without frames and battens. 

A f in. (19 mm.) thickness of crushed ice at 32F (0C) 
having a density of 36 Ib./cu, ft. (577 kg./cu.m.) and a 
latent heat of fusion of 144 BTU/lb. (80 cal./g.) will melt 
in a period of 7 days, AT being 30F (16.7C) and the 
U-value of the wall being 0.07 BTU/hr./sq.ft./F 
(0.34 kcal./hr./sq.m./C). A U-value of this magnitude 
is a common goal in land-based storage rooms main- 
tained at about 32F (0C). 

In fig. 182 the reference line for computing loss of 
space at the ceiling has been taken 2 in. (51 mm.) inwards 
from the flange of the steel frames in both the insulated 



! 1 




flf.182. Spac* but a^am for thelW*s& of a *t*l trawler 
[212] 



FISH HOLDS ENGINEERING AND ARCHITECTURE 



and non-insulated holds, which corresponds to the ceiling 
surface <rf the iKm-itwilatedhokL 

Heat transmittanoc calculations have been made 
using the standard formula: 

Q=UA AT where U=thermal transmission factor as 

defined in Appendix 1 
A area of the surface through 

which the heat flows 
AT^tempcraiurc difference between 
the extreme surfaces of the 
structure 

The thickness of ioe, D , in the wooden boats may be 
obtained from fig. 180 and 181 by subtracting D l in 
column 1 from D, in the abscissa. Note that in the 
non-insulated wooden vessel OU=0) the space lost 
at the ceiling, D a , is equal to the depth of crushed ice 
used, D,. 

For the non-insulated steel vessel, the thickness of ice, 
D t , may be obtained from fig. 182 by reading the number 
in the abscissa at which the curve in question meets 
Lio,=O. In this case, the space lost at the ceiling is 
equal to the depth of crushed ice, D,. 

The calculation requires an additional step for the 
insulated steel vessel. First add 2 in. (51 mm.) to D C ~(D B 
2) in. read from the abscissa in fig. 182 opposite the 
point on the curve which denotes the thickness of 
insulation considered. Second, from the algebraic sum 
(D t ) thus obtained subtract the number D 4 in column 1, 
namely the ordinate of the curves. Thus, from fig. 182, 
when heat flow is uniformly continuous for 14 days, AT 
being 30F (16.7C) and the steel vessel having 6 in. 
(152 mm.) frames at 30 in. (762 mm.) spacing with 3J in. 
(89 mm.) flanges, the required thickness of ice is (2.4+ 
2.0 in.) 3.0 in. =1.4 in. (112 76 mm. =36 mm.). Here, 
the insulation is placed between and over the frames to 
a depth of 2 in. (51 mm.). 

By such a calculation it will be seen in fig. 180 that gain 
in stowage space may occur in the wooden longliner 
when storage is 5 days or more, with AT being 50F 
(27.8C) and 7 days or more with AT being 40F 
(22.2C), namely combined space occupied by insulation 
and associated covering together with crushed ice 
becomes less than the space occupied by ice when 
insulation is not used. This gain in space, of course, will 
continue only to a certain maximum thickness of insula- 
tion beyond which space is lost. For all practical 
purposes the minimum transmission factor without loss 
of too much stowage space [assumed extra loss about 1 in. 
(25 mm.) of space as the result of using insulation] is 
0.09 BTU/hr./sq. ft./F (0.44 kcal./hr./sq. m./Q corres- 
ponding to 2 in. (51 mm.) of insulation, when the 
storage periods are 5 days ( AT=40'F, 22.2'C) and 
7 days ( AT30*F, 16.7C) respectively. 

The curves for the wooden trawler in fig. 181 indicate 
that gain in stowage space occurs with the use of insula- 
tion when storage is for approximately 14 days, AT 
being 40*F (22^C). For the practical case where not 
too much stowage space is lost against the surface* the 
minimum transmission factor would be 0.10 BTU/hr./ 



sq. ft./F (0.48 kcaL/hr./sq. m./Q, corresponding to the 
use of 1 in. of insulation, when the storage period is 
7 days ( AT40 to SO'F, 22.2 to 27.8Q and 0.08 BTU/ 
hr./sq, ft./F (0.39 kcai/hr./sq. m./C) corresponding to 
2 in. of insulation, when the storage period is 14 days 
( AT=*30'F, 16.7<C). 

Cain hi stowage space may occur in the sted trawler 
[when combined space occupied by ice, insulation, etc. 
becomes less than that occupied by a ceiling over an 
uninsulated structure together with the required ice] 
when storage is for one day, AT being 30*F (16-7Q 
depending on the thickness of insulation used between 
and over the frames as shown in fig. 182. For all longer 
periods, AT being 30F (16.7'C) or higher, a saving of 
space may result. For example, space savings of 11.0, 
10.9, and 10.3 in. (279, 277 and 262 mm.) result for a 
period of storage of 14 days, AT being SO'F (27.8C) 
for the cases where insulation is placed between as weO 
as over the frames to depths of 1, 2, and 3 in. (25, 51, 
and 76 mm.) respectively. 

It thus appears to be quite practical to insulate both 
between steel frames and over the latter to a depth of 
approximately 3 in. (76 mm.) without sacrificing fish 
hold space when storage periods are 3 days or longer and 
AT being 30F (16.7C) or higher. The diagrams 
indicate that, generally, insulation can be used more 
advantageously on the steel than on the wooden vessel. 

Influence of insulation on quantities of ice to be carried 

The quantities of ice to be stowed against the ceiling to 
combat heat flow for a period of 7 days, AT being 40F 
(22.2C) are determined with the aid of fig. 180, 181, and 
182, according to table 50 (see p. 226). 

Water-vapomr proof membranes. The best available 
vapour barriers and insulations should be selected and 
their application is most important. Normally, resistance 
to diffusion of moisture by the material covering the 
warm side of the insulation should be maximum, that of 
the material on the cold side should be minimum and that 
of the insulation some intermediate value. 

The wet fish hold, finished on the inside with a water- 
tight covering, needs little maintenance and is better for 
stowing fish than its poorly finished counterpart. Unfor- 
tunately such a highly resistant surface to the flow of 
water vapour is undesirably located on the cold ride of 
the wall. Unless great care is taken to provide an 
efficient vapour barrier on the warm side or to prevent 
water vapour from passing through the insulation, such 
as in the Minikay system (Bain, 19S5a), condensation in 
the insulation can be expected. The problem is not as 
significant in the steel boat where the plating acts as a 
good vapour barrier, or in the wooden boat where a 
vapour barrier of lowest permeability is applied to 
members and materials in situ in the walls and in heat- 
resisting partitions and decks. 

No universally accepted standard of water vapour 
resistance exists. The Owens-Corning Fiberglas Corp., 
1953, recommended that vapour barriers have a resistance 



[213] 



FISHING BOATS OF T!* WORLD: 2 CONSTRUCTION 



of 0.2 grains/q. ft. of surface/in. Hg, pressure diJflferen- 
tiaVhn (=0a penns) for storages above 30F (16.7C), 
and th appears to be satisfactory. 

Quo of the mot suitable materials for ships is bitumen 
(Bell, 195?) applied as either a gel-type cutback (used 
with a petroleum solvent) or a get-type bitumen latex 
emulsion, in thicknesses of up to i in* (3*1 mm.) to give 
a dried film of approximately ^ in, (1.6 mm.). In using 
the former* the space should be well ventilated and 
sufficient time allowed for the solvent to evaporate before 
covering with insulation. 

Vapour barriers in sheet form, e.g. aluminium alloy 
foil or polyethylene, require considerable care in placing 
and are not particularly suitable for boats. 

Specifications and inspections should ensure that the 
vapour barrier entirely covers all warm surfaces in one 
continuous layer. A good vapour barrier should also be 
used when the insulating material has a high moisture 
resistance. 



There is a wealth of general information on insulating 
materials. For boat use, the following combined qualities 
should be sought: 

Suitably low conductivity coefficient 

High resistance to the diffusion of water vapour 

High resistance to water absorption 

Suitable density 

Suitable compressive strength 

Suitable resistance to rot 

Dimensional stability under varying temperatures 
and humidity 

Suitable resistance to flame 

Availability and low price 

The following types of insulation will be considered: 

^ Cellular, namely corkboard, foam plastics (poly- 
styrene), expanded ebonite, cellular glass 
^ Glass fibre slabs 

> Those whose efficiency depends upon layers of air, 

e.g. aluminium foils in an alueolar structure and 

layered, crimped sheets of cellulose acetate 

For steel vessels where insulation is not load-bearing, 

resistance to water absorption is stressed, except perhaps 

when the insulation is used under the deck. For the 

wooden vessel, the insulation should also be resistant to 

rot. When it has to bear substantial loads, in both steed 

and wooden craft, high density and high compressive 

strength are needed. 

i to iv&tfcr awofftmi firo rot 

With die exception of cork, the cellular materials 
lifted qualify. Slabs of corkboard would be much 
more satisfactory if property coated on all sides with 
bitumen than untreated 

Glass fibres in uncoated stab form do not qualify. 
Coatings improve them 

Layered ahiminium alloy foils and cdtalose acetate 



Varkms 

The listed cellular insulations qualify in various degrees 
for load-bearing applications as do some of the heavier 
glass fibre materials, but none of the alloy foils or cellulose 
acetate sheets qualify. 

Polystyrene is not recommended (Seiffert, 1956) where 
temperatures are above about 150F (66C). Expanded 
ebonite could burn if acetylene welding or cutting were 
carried out on adjacent steel plates. One solution is to 
use a non-inflammable insulation, e.g. cellular glass or 
glass fibres next to the steel plates, and other cellular 
materials, such as expanded ebonite or polystyrene for 
the inboard layers. Where interior linings or tank sides 
constituting the walls are also welded, the use of cellular 
glass could be indicated throughout, although com- 
promise solutions would still be possible. 

Air circulation within the insulation 

Air can circulate across the cavities of an insulating 
material in situ where these are porous or are of crimped 
sheets, such as aluminium foils and cellulose acetate. 
There are sealing difficulties at the joints of layered, 
crimped sheets. 

FEATURES CONDUCIVE TO EFFICIENT 

AND SAFE WORKING 
Hatches 

If each fish room has at least one large hatch, bulk- 
stowed fish can be quickly unloaded by the batch, 
continuous conveyor or bucket method and unloading of 
boxed fish can be facilitated. MacGregor hatches 
(Bain, 19S5b) may be fitted. Large hatch covers need 
not be opened at sea. A successful method (Eddie and 
Waterman, 1958a) is used in newer British trawlers in 
which the larger hatch covers are fitted with screw- 
down manholes for access and for a chute from the fish 
washer erected above the hatches. Where deck-level 
wash boxes with screw-down fish valves are preferred 
and deck space is not available for separate wash boxes, 
the wash box could be built integral with the centre 
section of a MacGregor cover or a large cover of the 
conventional type. 

Lighting 

There should be a generous supply of flat marine type 
lights placed off-centre as nearly in line with transverse 
rows of stanchions as possible and protected by the 
stanchions. Three-way switches should be provided as 
well as a warning light visible from the bridge. 

Mostfiflh hold ladders are skimpy and some arc extremely 
dangerous. The rung-and-stringer type is better than the 
one having steps OH both sides of a pillar. Pillar-ladders 
located along the centre line of the fish hold slow down 
fish handKng, and they are also dangerous. 

A vertical runf-and-ttrin0er ladder should preferably 
be of met a!i Rungs should have a maximum spacing of 
12 in, (305 mm,) and stringers at least 15 in, (381 mm.) 
apart. 



(2141 



FISH HOLDS ENGINEERING AND ARCHITECTURE 



Central gurry troughs should have skid-proof perforated 
metal covers. All fish room floorboards should be 
skid-proof. 



o* facilities 



Drafeafe art wai 

Where pens extend down to the tank top or to the bottom 
of the fish room a tier of horizontal shelves should be 
provided at least 2 or 3 in. (51 to 76 mm.) above. Cor- 
rugated metal shelf boards assist drainage to the sides of 
the pens. 

It is essential that fish pen drainage is unhampered 
and that free flow to the sump is maintained. Drainage 
can be assisted by stops at the bottoms of stanchions to 
prevent division boards from dropping. Another way to 
stop this is shown in fig. 1 86 illustration A. 

Gurry troughs through the centre of fish rooms should 
be of generous size, isolated from the bilges, and should 
not carry piping or other facilities restricting flow or 
creating a cleaning problem. 

The sump should be of ample capacity, watertight and 
completely isolated from the bilges and it should have a 
perforated cover. It should be possible to empty the 
sump by means of one or more power-driven pumps, 
independently of the bilges. Standby pumping arrange- 
ments for deck manipulation should be provided. Suction 
intakes should have strainers. An excessive liquid 
warning device is useful. 

Hot water for cleaning fish rooms can be supplied by 
hoses through the hatches or by fixed pipes. Fixed pipes 
avoid confusion and overcrowding at the hatches and 
on deck, but provision must be made to prevent them 
from freezing when not in use. 

PARTITIONS, SHELVING, ETC. 

Transverse partitions 

These are considered separately from ceilings. Pigeon 
holing the catch gives some of the benefits of boxed fish 
without the inconvenience of handling empty boxes. 



Its effectiveness depends on the use of portable and 
interchangeable movable boards in most of the pigbon^ 
hole structure. Transverse partitions may be fixed as 
shown in fig. 183, movable as shown in fig. 184, 185, 186 
or a combination of the two. 

Fixed wooden components get wet even when painted, 
and this has led to the use of many portable boards in the 
hope that repeated cleaning, drying, and painting win 




Fig. 184. Fish pens with movaMe wooden boards for transverse 

partitions, pen divisions and shelving. Note the discontinuity of 

battens at stanchions, and dependence on batten boards to assume 

vertical and side loads 



keep them in a better state. Some aluminium alloy 
portable boards compare favourably in cost with painted 
wooden boards. 

Other factors involved in the choice of movable or 
fixed partitions are: * 

Shelf supports, being standard angles on fixed wings in 
fig. 183, are apt to cost less than some of the special 
extrusions in fig. 185, 186, illustration A, used with 
movable partitions. However, standard angles can be 
used for portable boards in wings in fig. 1 86, illustration B. 




193. Fish ent with a fixed transverse f*n 
KMdama&tothe 

[215] 



FISHING BOATS OF THE WQRU>: 2 CONSTRUCTION 




Flf.l&S. FUkpwwttmovabkcorriifated aluminium afoy boards 
far transverse partitions, pen divisions and shelving. Not* the dis- 
conrtmdty of batten* * stancUons and dependance on those transverse 
boards wkk wUck the skeff hoards art in contact to assume vertical 
and side loads 

Loads can be taken on transverse portable boards to 
which the shetf board battens are fixed or on which they 
rest as shown in fig. 1 84, 1 85, but this is not recommended, 
because excessive side loads may be experienced. A 
satisfactory solution is shown in fig* 186. 

In general, the most important improvements in 
connection with movable elements in transverse partitions 
of large trawlers would be: 

Loading directly onto the stanchions through 
suitable battens 

Arranging stanchions so that all movable boards 
are interchangeable 



Uak Pea 



The Unit Pen (fig. 187) provides pen partitions and 
pen bottom and back in integral unit form (MacCallum, 
19548, 195Sa). Each aluminium alloy pen illustrated 
is made of three prefabricated sections. 
The advantages of the Unit Pen arc: 
% Effective welding methods can be used 

The units can "work** freely without the welded 
joints breaking 

Heavy sheet or light plate can be used 

Unit Pens can be removed readily and replaced for 
hull inspection or repair 

Washing the pen between trips becomes a smaller 
problem than when wholly "built-up" pens are used 

The main disadvantages are high first costs and wasted 
pace behind them when Unit Pens are placed in fish 
rooms of non-uniform shape or in those in which the 
shape changes rather abruptly from full to narrow Hues. 



widths 



Pens should not be tew than about 3 ft. Sin. (LI m.) wide 
for best working conditions. 



The number of portable shelve* should be decided on the 
baits of the fishery needs and on amort practke. In 



areas where they have not been used before in fish holds 
up to about 6 ft. (1.8 m.) in depth, a bottom shelf to 
provide drainage and one additional shelf just below the 
mid-point of the pen height would be practicable more 
would not be profitable. 

Specific shelf positions as indicated in fig. 183, 186, and 
187 are to be preferred to indefinite positions indicated 
by the arrangements shown in fig. 184 and 185 because 
in the former cases the shelves are more apt to be used. 

Shelf supports 

Undesirable side thrusts can be caused when shelves are 
jammed by pieces of ice and careless placing of the boards. 
This will occur more often when the location of the 
shelves is not specific as shown in fig. 184 and 183. 
Damage caused by side thrusts could be prevented by 
using heavier boards in transverse partitions as shown in 
fig. 184 and 185, but better still such loads can be taken 
by shelf supports and stanchions as shown in fig. 186, 
in which case lighter transverse boards may be employed. 

COATINGS AND LININGS 

Fish room paints can be classified as follows : 

Those with a hard-drying phenolic resin modified 
with specially formulated oil alkyd 

Shellac paints 

Plastic base paints requiring the addition of a 
catalyst 

Plastic paints and varnishes containing epoxy resins 
require renewing yearly in whole or in part. None of 
them completely prevent the wood from getting wet in 
service, and they cost about twice as much as other 
types. The covering capacity of both plastic and non- 
plastic paints is about 500 sq. ft. per Imp. gal. (10.2 sq. m. 
per litre). Epoxy compounds in contrast to epoxy 
paints have much lower covering capacity. 

The application of plastic paints is somewhat more 
complicated than that of conventional coatings, and the 
manufacturer's recommendations should be carefully 
followed. 

Canadian experience is that fish hold paints should 
preferably be white with grey and aluminium finishes as 




Flf.186. 



toy tki ******* ore Mrf to met*** 



1 216] 



FISH HOLDS - ENGINEERING AND ARCHITECTURE 



the next choke. With time, the degree of covering may 
be judged effectively, an impression of cleanliness it 
realized and the effects of wear may be judged readily* 

MATERIALS FOB FISH ROOMS 

Materials in wet fish holds should be: 

(a) Suitable for storing foodstuffs (MacCallum, 1954b; 
1955a; 1955b; 19S6) 

(b) Sufficiently strong 

(c) Waterproof 

(d) Suitably resistant to corrosion and wear 

(c) Of light weight where portability is required 

(f ) Of light colour or painted a light colour, preferably 
white 

(g) Inexpensive 

AH items except (e) apply in whole or in part to fixed 
partitions, portable boards and most linings, and (e) may 
apply in the latter case when screens are used to cover 
ceilings. 

Characteristics of aluminium alloys are referred to in a 
published Bulletin (MacCallum, 19SSa). 

The magnesium and magnesium silicide group of 
wrought alloys, heat-treatable and non-heat-treatable, 



are recommended. These metals have good physical 
properties (Aluminium, 1957a), excellent resistance to 
corrosion in marine environments, and good wcidabiKty 
with the comet equipment (Aluminium, 1957b). In 
general other groups should be avoided, particularly the 
copper group. 



AM4LC AND ALUMMIUM BTAMCHKM 




CUT Hum THUS AT 

TOP rot mscuno 

Or POUND OAflO* 




OOUNTIMUMCHUO 
HfVtTt 



GALV.MSI 



-ALUMNMJM EXTKUftON 




187. A V*it K* instated i* the fi* room of the 
CtpcArfoi 



Fig. 188. Method of fixing aluminium alloy stanchions in fish 



Designs and specifications should be prepared with 
care, taking advantage of assistance available from 
aluminium producers. 

Even with the alloys most resistant to corrosion, 
serious corrosion may result from poor fish room design. 
This can be avoided if: 

Aluminium alloy linings never rest on steel stiffeners 

The sheets are of adequate thickness to resist 
puncturing 

Other metals are isolated from them by at least 1 in. 
(25 mm.) air space. Where passage must be pro- 
vided through aluminium altoy structures, a thick 
electric non-conductor should be used to separate 
the other metal from the aluminium alloy 

% Aluminium alloy stanchions and stiffeners are 
suitably isolated from steel members as shown in 
fig. 188 and 189 

All fastenings used in connection with aluminium 
alloys are: (a) aluminium alloy; (b) zinc or cadmium 
coated if of steel (copper, brass or bronze should 
never be used) ; (c) non-metallic 

Portland cement concrete in fig. 189 and plaster ate 
not poured or laid against aluminium alloys 



1217J 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



To be considered bere arc: 

Wood phw coatings and shielding of wooden boards, 
metal boards and metal screens. In wooden vessels, such 
structural members as deckbeams are included in the 
term "lining" where these form part of the inner storage 
space (as in uninsulated boats). All exposed woodwork 
in a wet fish hold tends to gain in moisture content 
after a short period of service despite the use of paints 
and coatings* Only woods with the highest resistance to 
fungal attack should be used in fish rooms, deck beams 
and frames included. 

In the spring of 19S8 a thick epoxy compound was 
applied to the rather imperfectly dried linings of two New 
Brunswick small trawlers with a good measure of success. 

If it is known from experience in a particular fishery 
that added protection to that offered by paint is going to 
be needed, several possibilities exist: (a) at the time of 
building, the bare wood may be covered with glass fibre 
reinforced plastic; (b) portable wooden or metal boards 
may be provided to protect well-painted linings and 
bulkheads ; (c) metal screens may be used as panels for the 
same purpose. 

Polyester resins without reinforcement cannot be used 
successfully on fixed partitions and ceilings of trawlers 
which have been in service. A combination of resin and 
glass fibre reinforcement is not impractical but some 
cracking, tearing and loosening will tend to occur after a 
period of two to three years (MacCallum, 1958). Success 
in laying the material and in service was achieved in two 
Newfoundland longliners built in 1957 and 1958 accord- 
ing to Monroe. No shovels or forks are used in these 
fish holds. 

The most economical use of these materials is on new 
woodwork on which one layer only of glass cloth is used 
with the resin. Structural strength is provided by the 
backing material which in the case of the ceiling may be 
the ship's sheathing. Where insulation is placed over 
the ceiling, i in. (6.35 mm.) thick marine plywood may 
be placed over the insulation as backing material for the 
"glass". 

Correct techniques must be used to obtain satisfactory 
results with glass fibre reinforced plastics. It is also 
essential that forced ventilation be provided during 
application to remove toxic gases and to reduce fire 
hazards. 

Portable boards to protect linings may be desirable 
on certain areas of the linings. These movable boards, of 
painted wood or aluminium alloy, can be removed for 
washing and drying, and repainted, if required. 

Metal screens can be used in the same way as given for 
portable boards above. There is the added benefit that 
screens in fig. 190 retain ice between them and the walls 
to which they are attached. (MacCallum, 1954c, 
1955a, 1956). 



Aluminium alloy: These are given in table 48 and 49 
far North Atlantic vessels. 



Partitions: These are discussed under "Transverse 
partitions" and "Integral transverse and Ceiling coverings 
the Unit Pen 9 *, above. 

Watertightness in linings: The use of aluminium alloy 
linings to provide water-tightness is feasible, but costs 
are high. Chilling in refrigerated sea water has stimulated 
the need for tanks involving quantities and gauges of 
materials and weldments similar to those used in the 
construction of the Unit Pen. (MacCallum, 1954a, 1955a.) 

The simplest and cheapest watertight lining is welded 
metal. The main objection is said to be that the wall 
beneath can be reached only by removing the lining, but 
efficiently gasketed access doors to the hull can be 
provided in the lining, and modern welding techniques 
are such that patching and rewelding of cut areas can be 
done rapidly. The alternative is to use movable units 
such as the Unit Pen (fig. 187). Mechanical joints as 
typified by British Patent Specification No. 799, 238 (1958) 
appear to be of exceptional quality. They should be 
differentiated from applications in which simple mechani- 
cal lapping of plates or butting of plates on wooden 
grounds is practised. Failures of applications of the latter 
type have occurred. 

Insulants used as seals in mechanical joints should be 
chosen with caution. The preparation of faying surfaces 
should be discussed with aluminium alloy suppliers. 

Pen boards 

The required characteristics of boards are the same as 
those outlined for materials for fish holds together with 
correct thickness and width; correct overall length; 
correct contour of ends. 

In the case of wooden boards some of these factors 
should be more fully considered along with additional 
aspects, such as: 

Checking: To prevent checks from developing, the 
timber should be properly seasoned and stored, and 
painted immediately the boards are cut. 

Thickness and width: In general, a softwood board of 
about 1 in. (25 mm.) nominal thickness can be used in 
widths of up to 6 in. (152 mm.) without fear of excessive 
loss through splitting; but thicker boards are often used. 

Shape of cross-section: Paint on softwood boards 
wears first at the square corners and then spreads to other 
areas (MacCallum, 1958). Whether or not a different 
cross-section will prolong the life of the paint has not 
been established. 

Length of boards and end cutting: Boards should be 
about t in* (12.7 mm.) less in length than the distance 
between the grooves in the stanchions. Their ends should 
be cut to an arc or otherwise dubbed off. 

With aluminium alloy boards the choice and design 
depends on the size, shape and distance apart of the 
stanchions, and the load or combination of loads the 
board wifl cany, Its design would be greatly simplified 
and com lowered by supporting shelf battens directly 
on stanchions. Boards 4 ft, 0*22 m,) long and f to 1 in* 
(23 to 25 mm.) thick, used as shown in fig. 186, are 
satisfactory. 



[218] 



FISH HOLDS ENGINEERING AND ARCHITECTURE 



TypfadwfcrW* 



TABU 48 
feyfl* 



Characteristic of 
material 


Floors and shelves of 
pens 


Celling 


Fixed 
partitions 


Movable 
partitions 


Butkktad 
covering 


Deckhead 
covering 


Stanchions 


Angbbars 
and other 
extrttsions 


Sheet Extrusions 


Alloy 




















(a) Canadian practice 1 


HA.4.57* 


HA.5.65 


HA.4.57 


HA.4.57 


HA.5.65 


HA.4.57 


HA.4.57 


HA.5.65 4 


HA.5.65 


(b) British equivalent 1 


1470-NS4 


1476-HE20 


1470-NS4 


1470-NS4 


1476-HE 20 


1470-NS4 


1470-NS4 


1476-HE 20 


1476-HE 20 


(c) British practice 


1470-NS4 


1476-HE10 1 


1470-NS4 


1470-NS4 


1476-HE 10 


1470-NS4 


1470-NS4 


1476-HE 10 


14764IE 10 






or 






or 






or 


or 






1476-HE 30 






1476-HE 30 






1476-HE 30 


1476-HE 30 


(d) Canadian equiva- 














1 




lent 


HA.4.57 


HA.4.57 


HA.4.57 





HA.4.57 


HA.4.57 




Filler alloy . 


Consult: Aluminum 


Welding and Allied Processes, Table 2-1-5, Aluminum Co. of Canada, Ltd., Montreal 


Gauge of material? 




















(a) Not backed by wood 
or other strengthen- 
ing material, other 


i to A in. 
(3.2 to 
4.8 mm.) 


Approxima- 
tely 0.082 to 
0.100 in. 


i to A in. 
(3.2 to 
4.8 mm.) 


Am. 
(4.8 mm.) 
(flat 


Approxima- 
tely 0.082 to 
0.100 in. 


iin. 
(3.2 mm.) 
(flat sheet) 


*in. 
(1.6mm.) 
or lighter 


" 


" 


than at tine of 


depending 


(2.08 to 2.54 


for lower 


sheet). 


(2.08 to 2.54 




(flat sheet) 






supports 


on centre 


mm.) for 3 to 


portion 


Possibly 


mm.) for 












to centre 


1 in. (22.2 to 


(flat sheet) 


iin. 


I to 1 in. 












distance 


25.4 mm.) 




(3.2 mm.) 


(22.2 to 










of 


thick 




when 


25.4 mm.) 












supports 


corrugated 




sheet 


thick 




i 






for flat 


boards used 




stippled 


corrugated 










sheet on 


to span up 




or 


boards used 


i 






floors 


to about 4 ft. 




otherwise 


to span up 










(1220mm.) 




beaded 


to about 4 ft. 












Approxi- 






(1220mm.) 














mately 


















0.082 in. 
















(2.08 mm.) 


















for i in. 




















thick 




















corrugated 



















boards used 






i 










to span up 


















to about 




















3 ft. 6 in. 










! 








(1,067mm.) 
















(b) Backed 


iin. 





iin. 








iin. 


A in. 





_ 




(3.2 mm.) 




(3.2 mm.) 






(3.2 mm.) 


(1.6mm.) 








(flat sheet 




for lower 






for lower 


or lighter 








on floors) 




portion 






portion 


(flat sheet) 












(flat sheet) 






(flat sheet) 














ilr in. 






*in. 














(1.6mm.) 






(1 .6 mm.) 














for upper 






for upper 














portion 






portion 














(flat sheet) 






(flat sheet) 









Hardness 



Non-heat treatable alloys of as high a work hardness as can be fabricated and erected successfully 

be utilized in sheets and plates 



1 Alloy numbers according to Canadian Standards Association (CSA). 
'Alloy numbers according to British Standards Institute (BS). 

British Standards Institute alloy 1477-NP5/6 [e.g. Noral B 54S (Northern Aluminium Co. Ltd., Banburv, U.K.) and Alcan B 54S(Aluminum 
Co. of Canada, Ltd., Montreal Canada)] may be an alternate choice when a major part of the fabrication work is by welding. There is very 
little low in tensile strength of this alloy as the result of welding as compared to BS 1470-NS 4, 

4 BS 1476-NE6 [Alcan A 56S (Aluminum Co. of Canada, Ltd., Montreal, Canada)] may be an alternate choice when stanchions are fabricated 
from individual extrusions and welding is a major factor. Cognizance should be taken of the relative mechanical properties of alloys 1476-NE6 
andl47-HE20. 

The nearest Canadian equivalent is HA 5.65. 

KJaiMeatf metal have been selected to reeist forest Gauges 

ccmW be reduced whe less rigoroiis U^tment is to be expected. In general it is easier to fabricate and erect heavy gauge sheets in Unit flan 
than it is in custom-built pen applications. 



{219] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 




r* to fttattc type. The ratttelaf afler* 



SIS 



Atutnlia Auttri* 
AA31S 



Germany 



Itdy 



Moral 518 

AlminalWlO 

BA25 

BirnwtalOtt 

Birmbrteht019 

DurmiuminX 

DuraUfcunft 



1U.FS 
SAl 



L. 107 



Spate SwitnrUuHl U.S.A. Ctmpotitb* 

AJodur533Cr 6051 Al-Mg-Si 

KonotetalCr 0.6 1 

AR5IS 
Al-Si-Mg 



T1441 

S-JS- 1200 



JJ/S 



Dakoral AleanBSIS Cmrbioi4 
S24 



Vtvl 
A-SG 



AlMfSI 

Aiuw4 
ErbdodiL41 



Fucte 3355 
HowI 



MWU4 



NoralB51S Antkorodftl 11 

Kynal M39/2 F177 

TI44I iMtorml 

TI 444 RE 2 

BA25 P-AlSilMfMn 

Durelumlo H 

HidumJoiuro44 

AlmlwUWM 

AWCO25 

BirmeUl071 

H30 



Aludur 533 
AntkoKxUl 
KorrofeKal 
KSB 

Al-Si-Mg 



Al-ft 



-Si 

i 



Fanul(43) 

PoUuJ 

UkmU 

VermasU 

Vmfel 

VolUl23 

ZimU 



548 AA54S 



Atetn54S 



Alumaf 35 

VB3 

VirpUum3 

A-O3 



AIMf 3 



Nora! 54S F.M. 3 

BA 27 Italkimag 35 

Birmabrifht 3 P 35 

Kynal M 35/2 Peraluiwn 35 

MG 3 P-A1 Mf 3.5 

TI 223 Alnurit 30 

AbttinalW5 

AltmwcMM 35 

HkhinJoiuin 33 

TI223 

AWCO 27 

N5 



Al-3Mg 



Al- 



3 M 5 



J54S 



Alcan B54S Heddenal 54 
CSAGM40 AIMf 5 



Moral B54S 
BAM27 



AR-B54S 



5083 
5086 



Al-Mg-Mn 
4.3 0.3 



BirmabrightS 
Kynal NI35/3 
Kynal M36 
IMG 3 
MG5 
T1224 

HMumtnium 35 
N5/6 



A56S 



Alcan A56S Alumag50 
CSA OM50N DonOlnox H5 

Sckral6 

A-G5 



NoralA56S 
BA28 

Birmabright 5 
Kynal M36 
MG5 
TI225 
AlmlnalW6 
AkinufMM 50 
Hiduminium05 
AWCO 28 
N6 



P-A1 Mg 5 



Aludur 500 
Al-5 Mg 



Al-Mg-Mn 
5 0.3 



57S 



A A57S Alramag 3 Alcan 57S 
CSA OR 20 



Alumag 25 Hydronattum Hy3 MG 2 
Carbinox 3 Peraluman 305 Moral 57S 
A-G2 AlMg 3 N4 



F.M. 2 
F.M. 24 
MNG3 



PwOumafi 
Al-3Mg 



30 



SAIL. H3 
Itattuma_25 
P. AlMg^.5 
Almarit25 



IAE201 
ASTMGR20A 



65S AA65S 



Afcan65S 
CSA GS I IN 



AR65S 



OSIIA 



Kynal M40 



[220] 



FISH HOLDS ENGINEERING AND ARCHITECTURE 



The fottawiagpoinUshouki be observed: 

Edges thouJd be square 

The flirtings of a corrugated board should be such 
that sharp ridges are not presented to the stowed 
fish. Some firms make reversible boards with left 
and right hand edges which avoids any difficulty in 
this respect 

Boards with many corrugations become slippery in 
the central work area. It might be simpler, safer, and 
cheaper to use wooden boards in this area 

A balance should be struck between the need to 
maintain a wide pitch of corrugations to reduce 
board weight and cost and the need to avoid a 
section which will fail through column effect. 

For length of boards and end cutting the same remarks 
apply as made for wood. 

Stanchions 

Wood should be used only for smaller vessels. Galvan- 
ized steel or aluminium alloys are suitable materials for 
medium and large vessels* In general, extruded aluminium 
alloy stanchions are better than those of built-up gal- 
vanized steel, and they are the same or a slightly lower 
price (Jefferson, 1958a). 

As to size, shape, strength and weight excellent advice 
concerning design of aluminium alloy stanchions can be 
obtained from some aluminium alloy sales development 
organizations. Fishery engineers probably have as good 
an appreciation as anyone of the necessary profile for a 
stanchion. The naval architect, of course, should have the 
last word in matters of strength. 

The principles involved in the proper attachment of 
aluminium stanchions to concrete floors are illustrated 
by fig. 189. 




9AIJMMIZID iTIIL 




f. 189, Method of fixing aluminium alloy stanchions in fish roams 
(CoittWy U ItovtM <* I* Aluminium) 



Fif. 190. Ufht weifht aluminium alby screens fabricated as panels 
are used over all fixed pen surfaces in the trawler Beauscjour II 



The cheapest method to attach studs or cleats to steel 
stanchions to support shelf battens is by welding. If for 
various reasons welding is not practicable, riveting 
(Jefferson, 1958b) may be substituted. 

Every effort should be made to provide a deck struc- 
ture which, combined with the regular fish room stan- 
chions, obviates the need for pillars on the centre line of 
the vessel near hatch coamings or under winches, etc. 

The use of glass fibre reinforced plastic for wet fish 
room linings, and aluminium alloys for stanchions, pen 
divisions and shelving might eventually become common 
practice. 

SMALL FISHING CRAFT 

Small fishing craft vary greatly in design and use, and the 
naval architect should consider each request for fish 
room and fish storage layouts and specifications according 
to the needs of the client. Nevertheless, it is possible by 
studying one basic craft to extract concepts concerning 
arrangement and use of materials which can be applied to 
other designs. 

LONGLINERS 

The basic design of the large Cape Island boat of 36 
to 42 ft. (11 to 13 m.) LOA, shown in fig. 191, has an 
open cockpit with a watertight floor made from 1J to 
li in. (29 to 32 mm.) wood. The floor is supported on 
cross-timbers laid on their flats athwartship above the 
keel and bolted to the underside of the knees. It is 
drained either by means of scuppers, with plugs, or by 
flow forward to a point aft of the engine, housed in a box 
as shown in fig. 191, thence to the bilges. Three hatches, 
flush with the floor, are fitted in each cockpit to give access 
to the space below. All fishing and stowage operations 
are conducted from the cockpit, the fish being taken from 
the power-hauled ionglines and stowed ungutted in a 
centrally located bin of maximum capacity of about 
6,000 Ib. (2,720 kg.), placed fore and aft of the engine box. 
Thwarts, on smaller boats, tie the vessel together just 
below the wash board. The floor is only a few inches. 



[221] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 




Fig. 191. Cape Island boats tied up at Claris Harbour, Nova Scotia, 

Canada 

above the top of the keel. Stowage and work space 
may be subdivided by transverse bulkheads of uncaulked 
softwood boards extending from the floor to just below 
the wash board. The thwarts may receive loose boards 
which are laid fore and aft to protect the catch from the 
sun. 

The planking is 1 to 1J in. (25 to 38 mm.) pine, 
caulked, puttied and painted outboard and treated with 
copper naphthenate on the inside. Steam-bent hack- 
matack frames of about j to 1 in. (19 to 25 mm.) thickness 
and varying in width from 3 to 5 in. (89 to 127 mm.) are 
used, clear distances between frames being approximately 
equal to frame width. There is no inner ceiling. 

Almost all areas and surfacing materials are subject to 
great wear. Insulated boxes are seldom provided for ice, 
and the fishing trip lasts for hours, not days. A canopy 
could be fitted over the fish bin, particularly if it were 
placed athwartship. An epoxy resin paint or similar 
coating might well be used on floor boards and bulkhead 
boards for smaller boats, and both inside and outside the 
bin for larger boats. The latter could be fitted with a 
grating for drainage. 

Insulated tanks or bins can be installed in the larger 
Cape bland boat at low cost because there is no upper 
deck. Bins should be well secured but easily removed, 
whether fitted or empty. In the former case it might be 
necessary to have a number of smaller units* The size 
would depend upon lifting capacity at the dock and suit- 
aide bin construction to prevent hogging and wracking. 



2 in. (51 mm.) or less insulation could be used in colder 
climates and 3 in. (76 mm.) or more in warmer. The 
material should be light and fire resistant where the bin 
or tank is fitted with a welded inner lining. Suitable 
materials for the linings are marine plywoods thoroughly 
coated with epoxy resins, glass fibre reinforced plastics 
and metal sheet or plate, such as weldable sea-water- 
resistant aluminium alloys, galvanized iron with soldered 
joints and steel covered with epoxy resins. Bin exteriors 
should be solidly made and have lifting lugs. Materials 
and coatings should be equal to lining material in 
resistance to dampness, water, and fish gurry, and should 
be able to endure the wear and punishment expected. 
Drainage should be provided in watertight bins, which 
should be suitably trapped to minimize the melting of ice. 
Condensing units and heat exchangers can be installed 
below the cockpit sole, forward of the engine, where 
mechanical refrigeration is required for chilling and 
storing the catch in sea water. The condensing units, 
circulating pumps, etc. can be driven by the main engine. 

LARGER LONGLINERS, SMALL TRAWLERS AND 
CUTTERS 

Lack of co-ordination between those concerned and of 
interest in the space which is to carry the pay-load often 
result in an unnecessarily small and irregularly shaped 
fish room. The owner often has to accept two or more 
odd-sized pens. Much more satisfaction could be achieved 
if the naval architect and builder were to recognize that 
this topic is as important to the prospective owner in the 
planning stage as discussion of main engines, winches, etc. 

Stanchions, hatches and "wings" 

Wooden craft of 45 to 65 ft. (14 to 20 m.) LOA are 
almost always fitted with wooden fish rooms housed 
below a full deck. One small hatch can give access to the 
fish room, or the hatch can be considerably enlarged, 
particularly in some longliners where the opening provides 
headroom in a shallow-depth craft. 

In selecting the size of hatch, a balance should be 
struck between space requirements for moving fish to and 
from the fish hold, deck space needed for fishing and 
gutting operations, and deck stowage space for small 
boats, while at the same time regulations concerning 
scantlings for hatches and hatch coamings must be 
observed. A hatch width of 3 ft. (91 cm.) should be 
considered minimum. 

Generally two rows of stanchions, one on each side of 
the fish room, are provided in a fore-and-aft direction. 
Where the upper ends of stanchions make contact with 
hatch-end beams, the centre-to-centre distance of the 
latter will be an even multiple of transverse and longi- 
tudinal stanchion spacing to provide complete inter- 
changeability of pen and shelf boards. In longliners, 
where the multiple is two, stanchions at the halfway 
position of the hatch may be secured to the underside of 
the hatch-dividing beam (strong-beam). In this case 
hatch width can be greater, equal to, or less than 
stanchion spacing. 



1222] 



FISH HOLDS ENGINEERING AND ARCHITECTURE 



When the stanchions make contact with the caritns, 
fore-and-afters, there cannot be complete interchange- 
ability of pen and shelf boards unless the transverse 
distance between the centres of these carlins is equal to 
the longitudinal spacing of stanchions. Thus the spacing 
of stanchions is established with an arrangement of this 
type once the width of the fish hatch is selected, and vice 
versa. 

A simple design for a stanchion, which has proved to be 
satisfactory, is used by an experienced builder (Wagstaff) 
in Nova Scotia, fig. 192. Although probably more 



and those used athwartships between inner rows of 
stanchions and those used for shelves. The advantages 
are that more of the fish room fittings can be removed 
for washing, drying, repainting or renewing; for equal 
deflections the material used in wing construction can be 
lighter than that required where a deep fixed wing is 
used, and there is greater flexibility in stowing tad 
unloading the catch. When there is one movable and 
one fixed section in each wing, the width of the fixed 
section can be reduced to between 3 and 4 ft. (0.9 to 
1 .2 m.) in any craft in this range of sizes. When costs 




Fig. 192. Right hand: section through the fish hold of a longliner showing conventional provisions 
for ventilation of between-frame spaces, as practised by Wagstaff and Hat field Ltd., Port 
Grevillc, Nova Scotia, Canada. Left hand: alternative method suggested by the author of venting 

space between frames 



costly than the ploughed section, it is cleaner, since its 
surfaces are easier to paint and repair effectively and 
cheaply by simple batten replacement. Where ploughed 
stanchions are used, the standing portions should be 
spiked according to Mines, The width of the grooves in 
the stanchions should be approximately i in. (6.3S mm.) 
greater than the thickness of the penboard. 

For larger boats an additional row of stanchions 
outboard of the first should be considered. Thus the 
normal fixed "wing" of the pen is broken down into a 
movable section between inboard and outboard stan- 
chions and a fixed section between the outboard row of 
stanchions and the fish room ceiling. The movable 
section is filled in with individual penboards inter- 
changeable with those used in the fore-and-aft directions, 



allow the series of narrow boards to be substituted, it is 
possible to use J in. (19 mm.) marine plywood or metal 
panels cut to the curve of the ship's ceiling. The plywood 
should be finished with epoxy resins or equally satis- 
factory coatings or with glass fibre reinforced plastic. 

Movable stancWons-Hthe boxing of fish 

In Denmark most fish is landed in boxes: exterior box 
dimensions, including handle bars at each end, are 
36 x!9#x 7} in. (914x500x187 mm.). The stanchions 
in the cutters are often removable to facilitate box 
stowage of herring. Empty boxes are often stacked on 
board in a wooden gallows on one side aft next to the 
steering house as shown in fig. 193. 
Galvanized iron is generally used for stanchions in 



[223] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 




193. Racks for aackiKt **&ty wooden boxes o* a new Danish 
steel trawler of about 100 tons and 80ft. (24.5 m.) length 

Cottrttsy Fldt*rtmi*ttt*rl*ti Fori+gslaboratortum. Cof9*h*s**, 



modern Danish cutters and in comparable Norwegian 
boats. Metal lends itself particularly to use in stanchions 
which have to be fixed securely yet must be capable of 
quick removal and be good for repeated service. 

Hadiig facOHks I or barrels 

Aboard some Norwegian vessels herring are salted in 
barrels on deck and the barrels are stored in the hold. 
According to Haraldsvik, the main requirements on 
deck are to have two or three bins in which to keep the 
fish before salting, and a good winch and hooks for 
handling the barrels. 



The holds should be readily accessible, and bins or 
pillars should not be fitted. The question has been 
raised by Traung whether tracks might be used efficiently 
and safely for the movement of barrels in the fish 



room. 



Shelving in pens in which the fish are bulk-stowed has 
the advantage that crushing is reduced and the whole 
catch can be more effectively segregated with respect to 
species and time of catch, thus facilitating discharge and 
subsequent disposal. For groundfish operations, shelving 
composed of individual movable boards can be used 
effectively every 2J to 3 ft. (76 to 91 cm.) of stowage 
depth. The Norwegian practice of placing the inter- 
mediate shelf slightly above the one third point of the 
pen height, measured from the bottom drainage shelf, 
appears to be sound. 

Pen drainage 

To facilitate drainage from each pen used for bulk* 
stowed fish, stops can be placed at the bottom of each 
stanchion to support bottom pen boards clear of the 
floor. Likewise, battens can be used at the bottom of all 
wings for a bottom tier of shelves which should be at 
least 2 to 3 in. (SI to 76 mm.) clear of the floor of the 
fish room. 



CeOingft, betweeo-fnu 



ttfl-deck-beams and stiffcner 



ventilation 

The need for ventilating the space between the wooden 
vessel planking and the ceiling is often given different 
significance from area to area. And sometimes a striking 
difference of opinion and practice exists among naval 
architects in a single area. The former differences are 
understandable in that species and characteristics of 




Fig, 194. 



32 GT and 46 ft. (14.1 m.) length 



[224J 



FISH HOLDS ENGINEERING AND ARCHITECTURE 



wood used, type of construction and temperature of 
water and air may be responsible for various degrees of 
resistance to fungal attack. 

Every boat owner, builder and naval architect should 
consider the need for ventilation. Ventilation installa- 
tion may be costly and the quantity of ice melted might 
be expensive from the standpoint of fish lost. Further 
investigations are needed. 

Aboard Esbjerg cutters, air circulation between frames 
is considered to be the cause of ice melting rapidly. 
Accordingly, provision is made to cut off air circulation 
while the fish are in stowage. To provide air circulation 
for drying when desirable and to allow washing behind 
the ceiling, a removable board is placed between each pair 
of frames where the ceiling meets the concrete, about half 
way up and again near the top of the ceiling in Skagen 
cutters and in the top and bottom positions in Esbjerg 
cutters as shown in fig. 194. 

Similar procedures in any other area would depend 
upon: 

(a) Ice losses due to continuous natural circulation of 
air behind the ceiling, e.g. the method used in Canadian 
longliners as shown in the cross- section shown to the 
right of fig. 192, where circulation is confined to the 
fish room only, and the method applied in some Nova 
Scotian small trawlers where means are provided for an 
exchange of air through a pipe and manifold system, 
between each between-frame space, throughout the whole 
of the boat, including the fish room, and engine room and 
forecastle spaces. 

(b) An assessment in the area concerned of the relative 
effect on fungal development of alternate wetting and 
drying of the enclosed woodwork as in the Danish cases, 
in comparison with environmental conditions associated 
with other designs. 

(c) Scale of scantlings used: Hines has indicated that 
scantling thickness has been reduced to a minimum and 
the cutting of sections from strakes in the inner ceiling 
cannot be tolerated in constructing Nova Scotian small 
trawlers. This difficulty could be avoided by increasing 
the thickness of the ceiling adjacent to the severed 
strakes, but in general the idea loses much appeal for 
craft such as those used in the Canadian Atlantic pro- 
vinces where fish rooms may change shape drastically, 
thus requiring that several strakes be cut on a bias. 



Were continuous air circulation, as in Canadian long- 
liners as shown in the cross-section on right of fig. 192, 
not desirable, the author suggests, at the left of the 
same figure, a modification of the Danish system for 
non-insulated and insulated longliners. Closing discs 
are provided on the goosenecks which are connected to 
pipes leading up the sidewall between each adjacent pair 
of frames. It is intended that the discs dose the pipes in 
front of the pens carrying toed fish or bulk ice. 

Where air circulation between the fish room and the 
frames' space of the non-insulated and insulated trawler 



is considered to be necessary, on a continuous or on an 
intermittent basis, a system similar to that shown for the 
longliner at the left of fig. 1 92 might be a solution. Hie 
spaces to be ventilated might be vented to the central 
work area by pipes embedded in the concrete of the 
fish room bottom in a vessel of the trawler type. 

Where loss of ice due to ventilation is serious, a 
remedy can be found if artificially refrigerated air is 
available. An application of this type is found in the 
trawlers Cape Fourchu and Cape Scutari (MacCatlum, 
19SSa) fig. 19S. A \\ in. (38 mm.) diameter pipe was 




Fig. 195. Section through the fish hold of the trawler Cape Fourchu. 

Two air circuits are in parallel, the ventilating air circuit outboard 

and the refrigerating air circuit inboard. The lower pipe in the 

d+awing is for draining the between-frame spaces 



started up each frame space from two S in. (127 mm.) 
diameter headers extending fore and aft at the bottom 
of the hold. There was a connection between 'tween- 
framc and 'tween-deck-beam spaces. The air supply 
for the ventilating circuit was bled from a refrigerated 
air supply which had a primary duty to maintain a 
temperature of about 31 F ( 0.5'C) within the jacket 
provided on the fish room side of the insulation. Thus 
the primary refrigerated air circuit and the ventilating air 
circuit were in parallel. About S per cent of the re* 
circulated, refrigerated air was made to pass through 
the ventilating pipes and into the 'tween-frames and 
'tween-deck-beams spaces* 



[225] 



PISHING BOATS OF THfc WORLD: 2 CONSTRUCTION 



and R- 



AFMMMX1 

thermal transmittanoe U t overall coefficient of heat trans* 
mission or transmission factor, across a wall expressed in 
BTU/hr./*F/sq : ft. or In taU,/hr,/C/5q. m. of wall surface is the 
fedpiocal of the total air-to-air or medium-to-medium resistance 
Rtothe flow of heat offered by the wall ; 

(1) 
- . Rn (2) 

*> -resistance at the inside surface of the wall to 
11 the (tow of heat where ft- inside film or 
surface radiation, conductance, and convec- 
tion in BTU/hr./sq. ft. of surface/ *F tempera- 
ture difference or kcal./hr./q. m. of surface/ C 
temperature difference between the surface and 
the surrounding medium, 

^--resistance at the outside surface of the wall to 
t the flow of heat where f = outside film or 
surface radiation, conductance and convection 
in BTU/hr./sq. ft of surface/ F temperature 
difference or kcal./hr./sq. m. of surface/ C 
temperature difference between the surface 
and the surrounding medium, 

Rn"*resistanoes of the various materials, of which 
the structure is composed, to the flow of heat. 



-, R B 



- j* 
- thickness in hi. 



L t , L* LQ thickness in hi. or cm. of 
each layer of homogeneous material in the 
wall and k lf k, k n thermal conductivity for 
1 in. or 1 cm. thickness of the corresponding 
homogeneous material in BTU/hr./sq. ft. of 
surfaoe/'F temperature difference or kcal./ 
hr./sq. m. of surf ace/ *C temperature difference 
existing across a unit thickness of the homo- 

i material, 



whence R 



showing tnat the resistance to the flow of heat 
increases with the thickness of the insulating 
materials. 



Therefore U ; 



+ C+LS+ _Ln (3) 

Where an air space exists in a composite wall 
and the conductance of the air is a, the 
resistance offered by the air to the flow of 
heat is I/a, hence this term will appear in 
the denominator of equation (3) along with 



Reference should be made to suitable hand- 
books for values of the constants in 
equation (3). 



TABLE 50 
Necesaary weight of crushed ke to carry boat heat flow for a period of 7 days 



Type of boat 
Wooden longhner 



Depth of crushed ice 
mm. 



Transmission factor 

BTU/hr./sq. ft./0F in. 

0.27 (no insulation) 4.2 107 

0.13 [1 in. (25 mm.) insulation + inner lining] 2.0 51 

Saving 2.2 56 



Weight of crushed ice 

Short tons (2,000 Ib.) Metric ton 

per 1,000 sq. ft. surface per 100 sq. m. 

surface 



6.2 
3.0 
3.2 



6.1 
2.9 
3.2 



Wooden trawler . . 0.1 6 (no insulation) 2.5 63 

0.10 [I in. (25 mm.) insulation dinner lining] 1 .5 38 

Saving 1.0 25 



3.7 
2.2 
1.5 



3.6 
2.1 
1.5 



Steel trawler 



0.37 (no insulation) 5.7 145 

0.08 (full insulation between frames. 1 in. 

insulation over frames + inner lining) 1.3 33 

Saving 4.4 112 



8.5 
1.9 
6.6 



8.3 
1.9 
6.4 



[2261 



ICING VERSUS FREEZING 

by 
JOSEPH W. SLAVIN 

A comparison is made of technological aspects of freezing and icing at sea. The freezing trawlers Delaware and Northern Wave art 
discussed in detail, and the procedures used aboard these vessels are evaluated in comparison with the procedures used on similar conventional 
trawlers, using ice. Emphasis is placed on (1) handling aboard the vessel, (2) storage on the vessel, (3) unloading and handling ashore, 
(4) quality aspects of frozen fish, and (5) the factors affecting the costs of freezing at sea. 

On the Delaware, brine-freezing round Ash prior to rigor mortis resulted in (1) slower handling aboard the vessel; (2) reduction of 
the vessel's capacity by 58 to 42 per cent., with capacity still higher, however, than the maximum capacity presently being utilized by Boston 
trawlers; (3) an increase in the time required to unload the vessel; and (4) increased handling at the shore-plant as compared with icing on 
the vessel. Brine-frozen fish stored at 0F (- 18C) for 8 months were of high quality; the texture was Arm, and the fish was easy to fillet 

On the Northern Wave, plate-freezing eviscerated fish after rigor mortis set in resulted in (1) increased handling aboard the vessel; 
(2) reduction of the capacity of the vessel by about 30 per cent.; (3) an increase in the time required to unload the vessel; and (4) excessive 
handling at the shore plant because of the large space and long period of time required for air-thawing the fish as compared with icing on 
the vessel. Plate-frozen fish must be stored at -20F (-29C) for maximum quality. Fish so stored were of high quality after 8 months; 
however, the texture was soft, and the fish were difficult to fillet. 

The factors affecting increased costs of freezing at sea as compared with icing at sea are (1) extra personnel required to operate 
freezing equipment: (2) additional cost of vessel due to freezing equipment and additional space required for storing frozen fish; (3) repairs 



and maintenance of freezing equipment; (4) insurance and depreciation of freezing equipment; (5) fuel for operation of freezer; (6) additional 
equipment and labour required for unloading the frozen fish; (7) frozen storage and associated handling costs ashore; and (8) equipment and 
facilities for thawing the frozen fish. Despite the increased cost of freezing at sea, sight must not be lost of its many favourable aspects; 



equipment and labour required for unloading the frozen fish; (7) frozen storage and associated handling costs ashore; and (8) equipment and 
facilities for thawing the frozen fish. Despite the increased cost of freezing at sea, sight must not be lost of its many favourable aspec 
namely, (1) the maximum utilization of the capacity of the freezer ship every trip; (2) the landing offish of uniformly high quality; and (3) t 
storage of frozen fish ashore during glut periods for processing and marketing during slack periods. It is recommended that new vessels 
built for freezing groundfish at sea rather than to convert existing trawlers, which are old and do not lend themselves to this application. 



LA MISE EN GLACE OPPOSEE A LA CONGELATION 

L'auteur compare les aspects technologiques de la congelation et de la mise en glace & bord. Les chalutiers congelateurs Delaware 
et Northern Wave sont examines en detail, et les procedures employees & bord de ces navires sont evaluees par comparaison a cellcs employees 
a bord des chalutiers similaires courants utilisant la glace. L'auteur insiste sur (1) la manipulation & bord ,(2) rentreposage a bora, (3) te 
dechargement et la manipulation a terre, (4) les aspects de la qualite du poisson congete, et (5) les facteurs affectant les couts de la congelation 
a bord. 

A bord du Delaware, la congelation en saumure des poissons entiers avant la rigor mortis a eu pour resultat (1) une manipulation 
plus lente a bord du navire; (2) la reduction de la capacite du navire de 58 & 42 pour cent, avec cependant une capacite encore plus grande 
que la capacite maximum utilisee actuellement par les chalutiers de Boston; (3) une augmentation de la duree necessaire pour decharger k 
navire; et (4) une augmentation de la manipulation a 1'usine a terrc par rapport a celle avec mise en glace a bord. Des poissons confides en 
saumure, entreposes a 0F (- 18C) pendant 8 mois etaient d'une qualite elevee, la texture etait ferme et il etait facile de fileter les poissons. 

A bord du Northern Wave, la congelation dans un congdlateur a plaques de poissons evisceres apres PetaWissemeirt de la rigor mortis 
a eu pour resultat (1) une augmentation de la manipulation & bord, (2) la reduction d'environ 30 pour cent de la capacite du navire, (3) une 




etaient de haute qualite apres 8 mois; cependant la texture etait molle et il etait difficile de les fileter. 

Les facteurs affectant I'augmentation des couts de la congelation en mer par rapport a la mise en glace & bord sont: (1) to personnel 



qui y sont associes, et (8) Pequipment et les installations pour decongeler les poissons congeles. En depit des couts plus eleves de la congefe- 




tion a bonl,ilnefautpMr^r^devuesejnombreux aspects favorably 
& chaque sortie, (2) to debarquement de poissons d* une qualite uniformement efevee, et (3) 1'entreposage a tern de poissons conades pendant 
les pcriodes d'abondance pour Ic traitement et la mise en vente pendant tos periodes creuses. L'auteur recommande que, plutot que de 
transformer les chahitiers existants, qui sont vieux et ne se pritent pas a oette application, on oomtniise de nouveaux bateaux pour congrier 
des poissons de chalut & bord. 

LA CONSERVACION EN HIELO FRENTE A LA CONGELACION 

El autor compara tot aspectos tecno!6gicos de la congelaci6n y de la conservacion en hido a bordo. Se examman con pormenoret 
treros congdadores Delaware y Northern Wave y los procedimientos emotoados a bordo de ellos se evaluan en comparacioii con 

mautorfc*iste(])inani^^ 



A tordo dei Zfetowor* la ci^ 
abQfdodeibsm,X2)iaf*^ 

[227J 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 

actua tmenic por lot airaslreros de Boston, (3) un aumento dd tiempo necesario para detcargar d baroo y (4) un aumento de la i 

n la ftbrica de tierra en comparaddn con d empleo de hide en d barco. El petcado congdado en sahnuera, almacenado a 0F (~18 3 C) 

durante t meses era de may buena calidad t de texturt firme y fAcil dc flletear 

A bordo dd Norther* Wave, la congelation en congdadores de pkcat de peecado eviscerado despues dd oomionzo de la rigor mortis 
multo (1) en un aumento de k manipulation a bordo, (2) en la reduction en 30%, approx., de k capacidad dd barco, (3) un aamento dd 
tiempo nocDstrio para dsscanjar d barco, y (4) excesi va manipulation en las fabrics do tierra debtdo al much o etpatio y largo tiempo necesariot 
para deacongekr d petcado al aire, en comperacion con ef petcado comervado en hielo. 1 petcado congelado en congdadorat de placas 
debe mantenene a 20F (-29C) para obtener la mejor calidad. El petcado afmacenado de etta manera era de gran catidad despues de 
8 metes, pero la tcxtura en Wanda y d petcado diffcil de fitetear. 

Lot iactorat que influyen en d aumento dd cotto de k congelation a bordo en comparacion con d emptoo del hido ton: (1) d 
pencmt timtaientario que hace falu para i^ 

y al etpetio tuplementario necesario para almacenar el petcado congdado, (3) las reparationet y roantenimtento dd equipo de congelation, 
(4) d seguro y la depreciation dd equipo de coiigelaci6n,(5)dcombu*tibtoneccsa^ 

necetanoft para detcargar d petcado congelado, (7) d ahnacenamiento en frigorif icos y los costos de manipulation en tierra relaclonados con 
el, (8) d equipo y las mstalackmes para detcongelar d pescado congelado. A pesar dd mayor costo de la congelation a bordo no se deben 
perder de vista muchos aspectoa favorabtos entre los que estan: (1) aprovechamiento maximo de k capacidad dd buque congelador en cada 
viaje, (2) la descarga de pescado de calidad uniformementc alta, y (3) d almaoenamiento en tierra de pescado congelado durante perkxios de 
abundancia para tratarto y venderio durante epocas de eacasez. El autor recomienda que e constniyan barcos nuevos paracongelar a bordo 
k pssca de arrastre, en vez de transformar los arrastreros existentes que, ademas de ser viejot, no se prestan para esta aplicacidn. 



IN recent years much consideration has been given to 
the freezing of fish at sea. These considerations have 
been influenced by the limited period that fish can be 
satisfactorily stored in ice aboard the vessel, coupled with 
the need to fish farther away from home in order to 
return with a full pay load. Factory ships have been 
developed and are successfully being used by the U.K., 
West Germany, and Russia, for processing and freezing 
at sea. The high cost of these vessels and the problems 
in obtaining crews that are willing to stay at sea for 
several months at a time, however, have prevented their 
use in some countries, particularly the U.S.A. 

The freezing of fish aboard the trawler, without pro- 
cessing, has been suggested as a solution to the high cost 
and labour problem associated with the operation of 
factory ships. It was thought that such a freezer 
trawler would enable the fishermen to return to port with 
a full pay load of fish, which could be either processed 
immediately or put into storage for future processing, 
depending on market conditions. Two trawlers recently 
have been developed for freezing the catch at sea, without 
processing aboard. These are the Delaware (fig. 196) in 
the U.S.A. and the Northern Wave in the U.K. Many 
reports have been issued concerning their development 
and operation. The object is not to review these reports 
but, instead, from data concerning the development of 
these vessels, mainly the Delaware, with which the writer 
is directly associated, to compare the technological 
aspects of freezing and icing on the vessel. Emphasis is 
placed on handling, storage and equipment requirements, 
keeping quality of the fish, and unloading and dock-side 
processing requirements* Some information on the 
factors affecting the costs of freezing and icing is also 
given. 

The trawlers Delaware and Norther* Wmve 
The Delaware is similar in size to the large trawlers 
operating out of Boston. It measures about 148 ft (45m.) 
in overall length, 25 ft. (7.62 m.) in beam and has a 
depth of 15 ft. (4.57 m.), a gross tonnage of 303, and a 
enuring range of 8,000 nautical miles* 



The freezing method is: 

Whole haddock are frozen in a 0F (-18C) sodium 
chloride brine (22 per cent, salt by weight) immediately 
after they are landed on the vessel. The normal pro- 
cedure is to load the round fish into one or more of 1 1 
metal baskets, each having a capacity of 450 Ib. (204 kg.), 
located in the freezing tank. The baskets are moved by 
mechanical means through the cold brine. The fish are 
frozen in } to 4 hr., depending on their size, are unloaded 
from the tank, and are conveyed by a chute to the 
0F (-18C) fish hold, where they are stacked by hand. 
An ammonia absorption system, having a designed 
capacity of 25 tons of refrigeration (75,000 kcal./hr.), 
is used in connection with two heat exchangers to provide 
the necessary cooling of the brine and of the frozen fish 
hold. The freezing capacity is 1,000 Ib. (454 kg.) of fish 
per hour, in terms of small haddock. 

The Delaware has made several large-scale commercial 
trips. More than 50 short tons (45 ton) of brine-frozen fish 
were landed each time. These fish were distributed to 
fish processors and dealers, who thawed and filleted 
them. The fillets then were packaged, frozen, and 
marketed in the usual commercial manner. 

The Northern Wave measures about 188 ft. (57 m.) 
overall and has a beam of 28 ft. (8.5 m.) and a draught 
of 15 ft. (4.6 m.). The fish were eviscerated on board 
and then stored, with ice, in a "buffer" storage pen. 
After rigor mortis set in and before the third day of 
storage, the fish were removed from the buffer pen and 
loaded into one or more of the 16 vertical plate-freezing 
units. Each freezing unit was capable of producing 
three 63-lb. (29 kg.) slabs of frozen fish. The freezer 
had an average capacity of 500 Ib. (227 kg.) of fish slabs 
per hour. A period of 4J to 5 hr. was required for 
freezing. The frozen slabs of fish were then stacked by 
hand in the -20F (-29C) hold of the vessel. This 
vessel has made eight commercial-teak trips and has 
landed over 250 short tons (227 ton) of frozen fish. Much 
of the frozen fish landed hoi been distributed to fish pro- 
cessors and dealers who air-thawed it and marketed it 
in the chilled or smoked state. 



[228] 



FISH HOLDS ICING VERSUS FREEZING 




Fig. 196. The freezer trawler Delaware with no processing equipment 



Differences in opinion exist between British and 
U.S. researchers as the merits of freezing in brine prior 
to rigor mortis and plate-freezing after rigor mortis sets 
in; good results are reported for both procedures. 

Handling aboard the vessel 

It is well known that fish must be iced immediately to 
minimize the loss of quality. Evisceration, washing, and 
icing of the fish can be accomplished quite rapidly under 
commercial conditions. On a Boston trawler, for 
example, a crew of six men can eviscerate, wash, and ice 
about 5,000 Ib. (2,270 kg.) of fish within an hour after 
they are landed on deck. If the rate of catch exceeds the 
rate of handling, fishing must be stopped or the trawling 
period must be increased to allow more time to stow the 
fish. Similar handling rates are reported for British 
trawlers, using ice. 

In freezing at sea, the fish must be handled as rapidly 
as in icing, otherwise a loss of quality also will result. 
On the Delaware, six men can normally sort and wash 
1,000 Ib. (454 kg,) of round haddock, load these fish into 
the freezer, and remove an equal amount of fish from 
the freezer in about 15 min. In an hour, these fishermen 
could theoretically handle 4,000 Ib. (1,810 kg.) of fish 
both into and out of the freezer, which is slightly less 
than the rate of handling for feed fish. The freezing 
capacity is however not sufficient to permit the loading 
of 4,000 Ib. (1,810 kg.) of fish at one time. 

On the Northern Jffevt, the fish were first iced for a 
period of 12 hours to 3 days and then were removed 



from ice storage, put into aluminium boxes, and trans- 
ferred from the boxes to the vertical plate-freezer. The 
labour and time required for handling were therefore 
more than were those required on the Delaware or on 
conventional trawlers using ice. 

The capacity of the refrigeration system, the time 
required to freeze the fish, and the size of the catch must 
be given serious consideration in designing a freezer 
ship. The Delaware has a freezing capacity of 1,000 Ib. 
(454 kg.) of fish per hour, and not more than 3,000 Ib. 
(1,360 kg.) of fish can be put into the freezing tank at 
once without increasing the brine temperature excessively. 
Accordingly, if a catch of 6,000 Ib. (2,720 kg.) is landed, 
3 or 4 hr. may lapse before the last fish are put into the 
freezer. The capacity of the freezing system, therefore, 
must be based on the maximum catch that can be 
expected within a 24 hr. period; also, sufficient quantities 
of brine must be used to compensate for the large initial 
loads of fish. For Boston trawlers, a capacity of 2,000 
to 2,500 Ib. (907 to 1,130 kg.) of fish per hour would be 
satisfactory with sufficient quantity of brine to permit 
the loading of 6,000 'to 7,500 Ib. (2,720 to 3,400 kg.) 
of fish at once. Also, some space should be provided for 
icing the fish in the event of extra large catches. The 
freezing capacity for the Northern Wave of only 500 Ib. 
(227 kg.) of fish per hour, which is less than that of the 
Delaware* was thought to be adequate because of the 
method used to store the fish in ice for a mii|rifm^ift of 



3 days prior to freezing; thus, the storage of fish in toe 
served as a buffer, tending to smooth out the effects of 



1229] 



FISHING BOATS OF THB WORtU: 2 CONSTRUCTION 



ktfge and tmaUcitchca on the freezing load Itispossibte, 
however, that this capacity would not be adequate if 
relatively large catches were landed during the first 
several days of fishing. 



Storage on the 

Consideration must be given to the effect of freezing or 
icing on the storage capacity of the vessel, since the 
capacity governs the maximum pay load offish that can 
be landed. The capacity of the vessel on which the fish 
are stored in ice is in direct relationship with the available 
hold space, the quantity of ice used, and the size of fish. 
In freezing at sea, the capacity of the vessel is reduced 
over that of a vessel of similar size using ice, because of 
reduction of hold space resulting from the installation of 
cooling coils, insulation, and refrigeration equipment. 
The additional space required for storing frozen fish as 
compared with that needed to store iced fish further 
reduces the quantity of fish that can be landed by the 
vessel 

In storing iced, gutted haddock on Boston trawlers, 
the ratio of fish to storage space was found to be about 
45 Ib./cu. ft. (721 kg./cu. m.) of hold space. On British 
vessels of the Northern Wave class, the ratio of fish to 
storage space is said to be lower than that on Boston 
vessels, being about 32 Ib./cu. ft. (513 kg./cu. m.) of hold 
space. This is probably due to the additional ice used on 
British trawlers because of the long period of time that 
these vessels are at sea. 

The Delaware, prior to being converted to a freezing 
trawler, had approximately 8,000 cu. ft. (226 cu. m.) 
of hold space for the storage of iced fish. In the conver- 
sion, however, the hold space was reduced to about 
600 cu. ft. (17 cu. m.) for storing iced fish, presumably the 
last 2 days* catch, and 3,800 cu. ft. (108 cu. m.) for 
storing frozen fish. Thus, a reduction of 3,600 cu. ft. 
(102 cu. m.) or 45 per cent, in space available for fish 
storage resulted. The reduction in space was attributed 
to the following: freezing tank and brine piping 
800 cu. ft. (23 cu. m.); refrigeration machinery 1,300 
cu. ft. (37 cu. m.); and insulation, bulkheads, refrigerated 
pipe coils, and other miscellaneous lost space 1,500 cu. 
ft. (42 cu. m.). 

Also, only 33 Ib. of round brine-frozen fish could be 
stored per cu. ft. (529 kg./cu. m.) of hold space on the 
Delaware as compared with 45 Ib./cu, ft. (721 kg./cu. m.) 
for storing iced fish. This further reduced the pay load 
of fish that could be landed. In all, owing to the reduc- 
tion in hold space and the increased space required for 
storing frozen fish, a total reduction in carrying capacity 
from 360,000 Ib. (163,300 kg.) of iced fish as originally 
designed, to 125,000 Ib. (56,700 kg.) of frozen fish and 
about 25,000 Ib, (1 1,340 kg.) of iced fish resulted because 
of conversion to freezing at sea. Thus, die total earning 
capacity of the Delaware was reduced by approximately 
58 per cent. This loss in capacity could be decreased 
somewhat by installing the refrigeration machinery in 
the engine room rather than in the fish hold and by more 
efficient arrangement of bulkheads. These measures 



would result in an increase in the vessel's storage capacity, 
hi terms of round frozen fish, from 125,000 Ib. (56,700 kg.) 
to 185,000 Ib. (83,910 kg.) thus, if these changes were 
made, the earning capacity of the Delaware would be 
reduced by about 42 per cent, instead of 58 per cent., as 
compared with its original capacity in terms of iced- 
gutted fish. 

The Northern Wave, which is larger than the Delaware, 
had a fish hold of 18,000 cu. ft. (509 cu. m.) with a 
capacity of about 500,000 Ib. (227,000 kg.) of iced fish, 
prior to conversion to a freezer ship. This capacity is 
proportionately less per cubic foot of hold space than is 
that of a Boston trawler of similar size. It is reported 
that the Northern Wave, as outfitted for freezing at sea, 
had 10,000 cu. ft. (283 cu. m.) of space for the storage of 
a maximum of 280,000 Ib. (127,000 kg.) of iced fish and 
cold storage space for about 70,000 Ib. (31,750 kg.) of 
frozen fish. The earning capacity therefore was reduced 
only about 30 per cent, because of conversion to freezing 
at sea. This vessel, however, was equipped to freeze 
only about 20 per cent, of its total possible catch, whereas 
the Delaware was able to freeze about 83 per cent, of its 
total possible catch. If the Delaware were equipped for 
freezing only 20 per cent, of its catch, as was the Northern 
Wave, the reduction in its original capacity would be 
only 25 per cent. This comparison shows that as the ratio 
of frozen fish storage space to iced fish storage space 
increases, the total capacity of the vessel decreases. 
Careful consideration, therefore, must be given to the 
maximum quantity of iced fish that is to be landed in 
determining the feasibility of freezing at sea. 

The information presented above shows that freezing 
at sea results in a reduction in the maximum capacity of 
the vessel. In evaluating icing or freezing, however, one 
also must consider to what extent the maximum capacity 
of the vessel was utilized when handling iced fish, and 
how this capacity compares with that of the vessel as 
converted to a freezer ship. It has been observed that 
many vessels of the Delaware's size are now operating at 
30 to 40 per cent, of their maximum capacity. It also 
may be noted that the Delaware can utilize its hold 
space fully, every trip, and thereby operate at 42 per cent, 
of its maximum iced fish capacity, as now outfitted. This 
figure can be increased to 58 per cent, with more efficient 
use of space. Thus, theoretically, the Delaware has a 
higher level of productivity per trip than have many 
existing trawlers, using ice. For proper evaluation, 
however, the increased productivity of the freezer ship, 
as compared with that of iced trawlers, must be weighed 
against the increased costs associated with freezing at sea. 



Unloading aid banking 

To determine the feasibility of freezing at sea, one must 
compare the time, labour and equipment required for 
unloading the frozen fish from the vessel and for handling 
these fish at the shore plant with those required for the 
similar handling of fish iced at sea in the conventional 
manner. Costs and requirements for handling die frozen 



[230] 



FISH HOLDS ICING VERSUS FREEZING 



fish then must be evaluated by both vend operators and 
processor! in terms of the overall advantages of this 
technique. 



In the unloading of iced fish from a large Boston trawler, 
the fish are loaded from the pens to a basket, which has a 
capacity of 150 to 175 Ib. (68 to 79 kg.) of iced fish. The 
baskets of fish are then hoisted to the dock, and the fish 
are dumped into a weigh box mounted on a simple 
platform scale. Two scales customarily are used to weigh 
out the fish being unloaded through each of the two 
hatches on the vessel. The fish, after being weighed, are 
loaded from the weight boxes to carts or boxes and are 
hauled to the plant for filleting. About 16 men are used 
to unload iced fish, 6 in the hold, 4 on deck, and 6 on the 
dock. These 16 men can unload a large trawler at a rate 
of about 30,000 Ib. (13,610 kg.) offish per hour, which is 
a comparatively fast rate in spite of the primitive methods 
used. On trawlers of the Northern Wave class, the fish are 
handled somewhat similarly, except that a small hook 
often is used to transfer them from the hold to the 
unloading baskets. These fish are weighed into alu- 
minium kits of 140 Ib. (64 kg.) capacity, which are 
transferred to the auction hall. 

The procedure used to unload frozen fish from the 
Delaware consists of transferring the fish by hand into 
the unloading baskets, hoisting the baskets to the dock, 
and dumping the fish into boxes of 500 Ib. (227 kg.) 
capacity, in terms of frozen fish. The fish in the boxes 
are glazed by spraying with fresh water and then are 
transferred by mechanical lift trucks to the cold storage 
plant. Each lot of fish is weighed on a large platform 
scale, prior to being placed in the frozen storage room. 
The weight of frozen fish loaded by an experienced crew 
averages about 85 Ib. (39 kg.) per basket, which is con- 
siderably less than the figure of 150 to 175 Ib. (68 to 
79 kg.) for iced fish. This decrease in the capacity of the 
basket and the additional time required in transferring the 
fish to the baskets reduce the rate of unloading con- 
siderably. Recent tests show that, with two hatches being 
unloaded, a gang of 14 men can unload the Delaware 
at a rate of about 15,000 Ib. (6,800 kg.) of frozen fish per 
hour. This is a reduction of about 15,000 Ib. (6,800 kg.) 
per hour or 50 per cent, as compared with the rate of 
30,000 Ib. (13,610 kg.) per hour for unloading iced fish. 
Thus, on the Delaware* the time required to unload 
frozen fish is twice that required for unloading iced fish 
on similar vessels. 

On the Northern Wave, the size of the hatch openings 
was increased to facilitate unloading of the frozen fish. 
The slabs of frozen fish, averaging 63 Ib. (29 kg.) were 
hoisted from the hold on wooden skids. At the begin- 
ning of unloading only 4 blocks could be used per skid 
because of the limited hold space available for handling 
the fish. After an hour, however, when the hold was 
partially emptied, 12 Mocks could be unloaded on a 
single skid. It is reported that 10 men could unload 
about 70,000 Ib. (31,750 kg.) of frozen fish blocks from 



this vessel in 5 to 6 hr. or at an average rate of about 
12,500 Ib. (5,670 kg.) per how. Thus, on the Northern 
Wave, the reduction in unloading rate was similar to that 
which occurred on the Delaware. 

It is believed that the quantity of frozen fish unloaded 
per hour from the Delaware and the Northern Wa*e 
could be increased considerably by more efficient ar- 
rangement of the fish hold to facilitate more rapid 
handling of the fish and through the use of elevator type 
conveyors, which can transfer the fish directly into a cold 
store located on the dock. It is doubtful, however, if the 
application of these methods would increase the rate of 
unloading frozen fish to a rate that would compare 
favourably with the one for iced fish. 

Handling ashore 

Much of the groundfish landed in New England is 
marketed in the form of frozen fish fillets, whereas, in the 
U.K., groundfish are marketed predominately in the 
fresh (chilled) and in the smoked state. The purpose of 
both the Delaware and Northern Wave projects was to 
provide a source of high quality raw material that could 
be stored ashore during glut seasons and then be removed 
from the cold store as needed, thawed, and processed 
in the manner common to the trade. It was thought that 
this would keep the processors supplied with raw material 
during the slack season. 

In handling the fish ashore, the processor has to take 
into consideration, in addition to his normal processing 
requirements, the facilities and cost for storing the frozen 
fish and for equipment for thawing these fish prior to 
processing. 

The fish frozen aboard the Delaware can be satis- 
factorily stored in the cold store in large boxes in lots of 
500 Ib. (227 kg.). The frozen-storage charges are higher 
than those for packaged fish because of the increased 
space required per pound of fish and the extra handling 
required to glaze the fish. If the fish are processed in small 
quantities, the 'boxes can be removed from storage the 
day prior to processing, and the fish can be thawed over- 
night by keeping the box flooded with a continuous 
stream of freshwater or clean seawater at temperatures 
from 45 to 60F (7 to 16C). Only 3 hours is required 
to thaw haddock of normal size thus, if necessary, the fish 
may be removed from the cold store early in the morning 
and processed in the afternoon. Thawing the fish in 
boxes, however, would not be practical for a large plant 
having a capacity of 2,000 Ib. (907 kg.) of fillets per hour 
for an 8 hr. shift because of the large amount of storage 
space and the large supply of water required. Assuming 
a 33 per cent, fillet yield in such a plant, for example, 
approximately 48,500 Ib. (22,000 kg.) of raw material or 
97 boxes of fish would have to be thawed at one time. 
For handling large quantities of fish, thawing tanks made 
of wood or non-corrosive metal, therefore, should be 
installed in or adjacent to the plant Three thawing tanks, 
each having a volume of 825 cu. ft (23 cu, m.) and a 
capacity of 16,500 Ib. (7,480 kg.) of frozen fifth, would be 
suitable. The size of the storage tanks is based on a ratio 



FISHING BOATS OF THE WORLD; 2 CONSTRUCTION 



for flih of 20 Ib./cu. ft (320 kg./cu. m*) of available space. 
Assuming a 20F (1 TC) drop in the temperature of the 
coding water, about 1,250 U.S. gal. (1,040 hap. gal., 
4,730 L) per hour of 60F(16Q water would be required 
for each tank if the fish were to be thawed in 12 hr., 
nd 5,000 U.S. gal. (4,150 Imp. gal., 18,900 1.) per hr. 
would be required if they were to be thawed in only 
3hr. 

The blocks of fish frozen aboard the Northern Wave 
can be satisfactorily stored in the cold store on pallets 
or wooden skids. Since these fish are in block form, 
they can be packed more tightly than can the Delaware's 
individual brine-frozen fish and therefore will occupy less 
space in the cold store. It has been recommended, 
however, that these fish be stored at 20F ( 29C) 
rather than at 0F (-18C) as suggested for the fish 
frozen on the Delaware. It is doubtful if there are 
sufficient cold storage facilities available in the U.S.A. or 
in other countries that will meet such temperature 
requirements. 

Investigators working on the Northern Wave project 
recommended that the fish blocks be thawed in circu- 
lating 65F(18C) air prior to processing. The procedure 
followed was to remove the frozen fish from the cold store 
about 40 hr, before needed, lay the fish out on shelves 
in a specially designed room, and, with fans, maintain 
uniform circulation of the air over the product. Electric 
heaters were used to maintain the air at the required 
temperature. Under the above mentioned conditions, 
20 to 24 hr. was required for thawing the fish ; after which 
time, they were weighed out into 140 Ib. (64 kg.) capacity 
boxes and iced, prior to filleting or smoking. 

It appears that more space is required for thawing 
frozen fish with air than with water. In view of the 
requirement for more space and the long period of time 
required for thawing in air, air thawing might not be 
entirely practical for large scale commercial applica- 
tions, where 50,000 Ib. (22,700 kg.) offish may have to be 
thawed at one time. 

Quality aspects 

It is generally known that fish stored in ice aboard the 
vessel will remain at an acceptable level of quality for only 
a relatively short time, even though they may have been 
handled under ideal sanitary conditions. The acceptable 
storage period for eviscerated haddock may vary from 
8 to 16 days, depending on the handling, icing, and* 
techniques of sanitation. 

For freezing at sea to be a success, the quality of the 
thawed frozen fish must compare favourably with that of 
iced fish that has been properly handled. Nothing is to 
be gained by employing freezing-fish-at-sea techniques 
that will result in a product of lower quality; such a 
practice would have no possibility of financial success. 
Investigators on the Delaware and Northern Wave pro- 
jects have taken this into consideration and have con- 
ducted extensive laboratory and industry tests to deter- 
mine the quality of fish frozen at sea. 

In the Delaware project, 30 short tons (27 ton) of brine- 



fin 



ddock 



lined, processed, and marketed 



by 19 fish processors and dealers at regular intervals of 
frozen storage. The fish were put into the 0F ( 18C) 
cold store immediately after being unloaded from the 
vessel. Samples of fish were withdrawn from the cold 
store at bi-monthly intervals of storage by the partici- 
pants, who water-thawed and filleted them; the fillets 
were then packaged, frozen and marketed in the manner 
customarily employed in the frozen fillet trade. The par- 
ticipants also noted the quality of the fish as compared 
with regular iced fish, on a form prepared for this pur- 
pose, and sent their comments to the U.S. Fish and Wild- 
life Service. The comments showed that water-thawed 
brine frozen haddock could be filleted easily, that the 
fillets were of good texture, flavour and odour, and that 
they compared favourably in quality with iced fish. It 
was noticed, however, that these fillets were of slightly 
darker colour than similar fillets from iced fish and that 
they had lost the characteristic bright sheen of iced fish 
fillets. This darker appearance was not considered to be 
detrimental to the product, since much of the colour 
bleached out during subsequent frozen storage. 

The maximum acceptable storage period at 0F 
( 18C) for the brine-frozen fish was judged to be 
8 months. Subsequent laboratory tests conducted on 
fillets prepared from brine-frozen haddock at intervals 
of 0F (-18C) frozen storage verified these results. 
Other tests showed that the average salt content of fillets 
prepared from water-thawed brine frozen fish was less 
than 0.5 per cent, for both round and eviscerated 
haddock. These tests demonstrate that haddock can also 
be brine frozen at sea in the eviscerated form as well as 
in the round, uneviscerated state. 

In the Northern Wave project, over 250 short tons (227 
ton) of fish frozen at sea in block form were made available 
to fish dealers and processors who thawed and marketed 
the fish in the chilled and smoked state. Similar samples 
were also evaluated by project investigators at intervals 
of -20F ( 29C) frozen storage. 

It was found that fish frozen on the Northern Wave 
kept their quality for 8 months of storage at 20F 
(-29C) and that these fish could be satisfactorily 
smoked. Industry commented, however, that the thawed 
fish were softer or looser in texture than were good 
quality iced fish. Some difficulty was also experienced in 
cutting the fillets from the thawed fish. The fillets lacked 
the characteristic sheen of iced fish fillets, as did the fillets 
prepared from brine frozen fish in the Delaware project. 
Some of this sheen was restored by dipping the fillets 
in a 50-per cent, saturated brine solution. 

The aforementioned experiments indicate that the 
quality offish frozen at sea compares favourably with that 
of iced fish. It is believed that the brine freezing process 
used on the Delaware firmed up the texture of the fish, 
making them easier to fillet than plate frozen fish. Much 
of the fish on the Northern Wave was smoked; therefore, 
texture was not as important a criterion of quality as in 
the Delaware project, where the fillets were marketed in 
the frozen state. 



[232] 



FISH HOLDS ICING VERSUS FREEZING 



The question of whether or not freezing fish at sea is 
economically sound depends to a great extent on the 
nature of the fishery involved and on many other factors 
common to vessel and processing plant operations and 
marketing techniques. Many times, even though a pro- 
cess may be economically sound, unexpected equipment 
failures and labour or marketing problems may result in 
financial loss. The Delaware and Northern Wave both 
were commercial vessels converted to freezer ships. They 
were, at best, experimental vessels. A study of the eco- 
nomics of their operations would mean little, since much 
was learned that could be put to advantageous use in the 
design of a new freezer ship. The purpose here then is not 
to make an economic analysis of these freezing operations, 
but instead to present information on how freezing at 
sea can be accomplished best and on the factors that 
should be considered in preparing a cost analysis of this 
technique. 

Studies on the Delaware and Northern Wave projects 
indicate that conversion of an existing trawler for 
freezing at sea is costly and, in many cases, is not prac- 
tical because of the age of existing trawlers and the 
limitations placed on the freezing process because of the 
design of the vessel. It would be far better to have a new 
vessel built that is designed specifically for freezing fish 
at sea. 

In determining the costs of freezing at sea, the follow- 
ing should be considered, in addition to the costs associa- 
ted with the handling of iced fish : 

Factors affecting vessel costs 

Extra personnel required to operate freezing 
equipment 

Additional cost of vessel due to freezing equipment 
and additional space required for storing frozen fish 

Repairs and maintenance of freezing equipment 

Insurance for freezing equipment 

Depreciation of freezing equipment 

Fuel for operation of freezer 



Additional equipment and labour required for un- 
loading the frozen fish 

Factors affecting processor co0ts 

Frozen storage and associated handling costs 

Equipment and facilities required for thawing the 
fish 

For freezing at sea to be a profitable venture in a 
separate vessel-plant operation, the additional costs- 
associated with vessel operation must be offset by the 
return resulting from the landing of a full pay load. It i* 
probable that the processor would pay less for fish frozen 
at sea than for iced fish because of the additional expense 
in storing and thawing the frozen fish. This must also be 
taken into consideration by the vessel operator, since it 
would affect the price received for the catch. It therefore 
appears that the economics of freezing at sea become 
more attractive as the harvesting ability of the vessel 
increases. An integrated vessel-plant operation would 
seem to offer the best possibility of financial success. 
In such an operation, where prior to freezing at sea the 
plant only operated part-time owing to lack of fish, the 
financial gain due to full-time operation of the plant 
using frozen fish could be used to offset some of the high 
costs associated with vessel operations. 

Overall evaluation 

Freezing at sea, therefore, resulted in slower handling 
aboard the vessel, reduction of the vessel's capacity, an 
increase in the time required to unload the vessel,, 
increased handling at the shore plant and increased costs, 
as compared with icing on the vessel. However, these 
factors must be weighed against the more favourable 
aspects of freezing fish at sea; namely, the maximum 
utilization of the capacity of the freezer ship every trip, 
the landing of fish of uniformly high quality and the 
"stock-piling" of frozen fish during glut periods for pro* 
cessing and marketing during slack periods. 



[233] 



TUNA FREEZING 

by 
CHOMATSU DOKE and SEIGORO CHIGUSA 

Japanese tuna boats have highly developed refrigerating systems, because (i) they must operate in tropical waters, (ii) a fishing trip 
often lasts for two months or more. 

Modern tuna freezing systems are described in detail, and the study is intended as a reference for the tropical operation of other 
fishing vessels. 

LA CONGELATION DU THON 

Les thoniers japonais sont munis de svstemes de refrigeration tres de*veloppes parcc que (i) ils doivent operer dans ies eaux tropicales, 
<ii) une sortie de peche dure souvent deux mois ou plus. 

Les systemes japonais modernes pour la congelation du then sont decrits en detail et I'etudc est con^uc pour scrvir de reference 
pour la peche tropicale d'autres navires de peche. 



CONGELACION DE ATUN 

Los barcos atuneros japoneses tienen sistemas de rcfrigeraci6n muy perfeccionados porque (i) tiencn que pescar en aguas tropicales, 
<ii) con frecuencia los vtajes duran 2 meses y mas. 

Se describen con pormcnores los sistemas modernos empleados por los japoneses para congclar atun. Tiene por objeto la comuni- 
cacion scrvir de referenda para otros barcos que pescan en aguas tropicales. 



A S TUNA boats operate mainly in tropical waters, 
f-\ their fishrooras are insulated and almost all are 
JL JL equipped with refrigeration. The larger and more 
recently built tuna boats also carry freezing equipment. 
The cost of this equipment often amounts to 20 per cent. 
of total construction. 

METHODS OF PRESERVING THE CATCH 

Fresh raw tuna is much in demand in Japan. The larger 
boats on long trips, however, freeze the entire catch, 
while the medium-sized boats bring back some of the 
catch frown and the rest in the fresh and chilled state. 



Storage by coW sea ' 
With this method, catches are preserved in cold sea 
-water, which is cooled by crushed ice or evaporator grid,' 
to about 32F (0C). The water is led directly into the 
fishroom, and the gutted, round tuna are kept submerged 
by a weight on the top; sometimes crushed ice or newly 
cooled water is added during storage. This method is 
often used for short trips. Stowage is about 45 Ib./cu. ft. 
(0.72 ton/ cu. m.) of the fishroom. 

Gutted round tuna are stored in the hold, together with 
crushed ice, and fishrooms arc usually equipped with 
refrigeration to prevent the toe from melting. As air 
convection does not take place, evaporator coils are 



arranged on the bottom as well as sides, walls and 
ceiling, and special attention is given to draining the 
bilge water from the melting ice, which otherwise impairs 
the quality of the catches. The period of preservation 
should not exceed 45 days. Stowage is about 30 to 36 lb./ 
cu. ft. (0.48 to 0.58 ton/cu. m.). 

Many boats pre-cool the fish in chilled sea water prior 
to storage in crushed ice, e.g. the gutted catches are put 
into a sea water tank and cooled to about 32F (0C) 
for 2 to 3 hr. before storage in the ice hold. This is called 
the pre-cooling system (fig. 197). 

Freezing 

There are three systems for freezing the fish, namely: 
(i) air blast; (ii) contact; (iii) brine e.g. Ottesen type. 

Air Mast freezing. This is the most common method. 
Round or semi-circular gutted catches are put into a 
battery of refrigerating coil installed in the special freezing 
room, and are frozen by cold air blast of 13 to 22F 
(-25 to -30C), which is forced through the pipes 
by 2 to 3 h.p. electric blowers placed at the ends of the 
battery. The time necessary for freezing is 15 to 20 hr., 
and the rate of freezing is usually 5 to 10 ton per day. 
The pre-cooling system is sometimes used, in order to 
shorten the freezing time. 

Contact freezing. Contact freezing by means of plate 
freezers is mainly used for fillets. This is a highly efficient 
method, as it can be carried out two or three times 
repeatedly in a day. It is, however, seldom used because 



[234] 



FISH HOLDS TUNA FREEZING 



of the moll demand for fillets in Japan. Even if this 
equipment is installed, it is generally used only for about 
30 per cent, of the catches, the main part being frozen as 
round fish. 

Brine freezing (Ottesen's system, fig. 198). The brine, 
made by adding salt to water, is cooled to a temperature 
of to 6F (18 to 21C) by pumping circulation, 
the catches are submerged in this brine and frozen for 
10 to 12 hr. This method is sometimes used in larger 
boats requiring good freezing but this is not so suitable 
for the tuna because it results in crooked shape and the 
penetration of salt. Frozen round tuna are stacked in the 
fishroom at about 0F (-18C). Stowage is about 
36 Ib./cu. ft. (0.58 ton/cu. m.). Hat fillets are put into 
cartons and stacked in the fishroom, stowage being about 
45 Ib./cu. ft. (0.72 ton/cu. m.). 




Fig. 197. Tuna pre-cooling installation in the forward part of the 
deckhouse working on the principle of chilled sea water 



Examples 

Most large ships are completely refrigerated and do not 
use ice. A typical example is the following: 

Hoku Maru (1,200 GT), built April 1957 

Freezing capacity (combined freezing system): 66,000 Ib. 

(30,000 kg.) per day 

Bait hold: 152 cu. ft. (4.3 cu. m.), 32F (0C) 
Pre-cooling tank: 671 cu. ft. (19 cu. m.), 32F (0C) 
Freezing room: 8,190cu. ft. (232 cu. m.), -22F(-30C) 
Frozen fish storage hold: 63,700 cu. ft. (1,804 cu. m.), 

1.4F (-17C) 

Ammonia compressors: 
88.5 Japanese RT (1,160,000 BTU/hr., 
294,000 kcal./hr.) 150 h. p. . . 1 

58.8 Japanese RT (775,000 BTU/hr., 
194,000 kcal/hr.) 100 h.p. . . 2 



TABLE 51 

ia ft* hoMs of tfce 200 GT SmmiyoM 
Mar* N*. 26 art 32, Mlt 1958 



. U8cu. ft. (3.35cu. m.) 
32F (0Q 

. 470 cu. ft. (13.3cu.m.) 



2,383 cu, ft. (67.5 cu. ,) 
-22F (-3 



Pre-cooling tank . 
Preparation room . 
Freezing room 



Frozen fish storage hold . 7,097 cu. ft (201 .0 cu. m.) 

1 ,4F( - 17C)aiid - 1 3.0"F(- 25*Q 



Condensers, horizontal shell and tube types: 



3 ft. (910 mm.) diam. x 11 ft. 10 in. 

(3,600mm.) effective length x| in. 

(16 mm.) plate thickness 
Inner tubes, 2 in. (50.8 mm.) diam. 
Effective area ..... 

Propeller fans, 3 h.p. 



2 

120 

1,069 sq.ft. 

(99 sq. m.) 

14 



An example for a boat of 250 to 300 GT is given in 
table 51. The principal machinery is: 

Ammonia compressors: 

36 Japanese RT (475,000 BTU/hr., 

120,000 kcal./hr.) 75 h.p. . . 1 

15 Japanese RT (198,000 BTU/hr., 
50,000 kcal./hr.) 30 h.p. . . 1 

Condensers, horizontal shell and tube type: 

2$ ft. (760 mm.) diam. x 9 ft. 10 in. 

(3,000 mm.) length . . .1 

Inner tubes, 2 in. (50.8 mm.) diam. . 80 

2 ft. 2 in. (660 mm.) diam. x 5 ft. 11 in. 

(1,800 mm.) length . . . .1 
Inner tubes, 2 in. (50.8 mm.) diam. . 48 
Propeller fans, 2 h.p. . . .3 

3 h.p. . . .2 



REFRIGERATING CAPACITY AND PIPING 

Refrigerating capacity 

The values in tables 52 to 54 are standard capacities for 
the direct expansion system: 20 per cent must be added 
to the capacities in the case of indirect cooling. 

Pre-cooling teak: For the pre-cooling tank, the 
refrigeration capacity can be selected from table 32. 

Freezing room: The freezing capacity in relation to the 
refrigerating capacity for various types of freezing is 
given in table 53. 

Storage hoM: The refrigerating capacity of the fish 
storage hold is given in table 54. 



[235] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



TABLE 52 



Pre-cooting capacity 

per 24hr. 
3 ton (6,600 !b.) 

5 ttm (1 1,000 Ib.) 
10 ton (22,000 Ib.) 



Refrigerating capacity, Japanese RT 
(13,175 BTU/hr. or 3,320 kcal./hr.) 

7.3 
14.5 



The standards for cooling coils in the direct expansion 
system are given in tables 55 to 57. In the indirect 
cooling system, the figures are increased by 20 per cent. 



TABLE 53 



; tank: Pipe lengths in the pr^ooottng tank 
or sea water cooling hold are given in table 55. 

Rearing mm: Table 56 shows the length of pipes for 
given refrigerating capacities. 

Storage bold: Table 57 gives the pipe fitting ratios 
corresponding to fish hold spaces, other than those listed 
in tables 55 and 56. 

INSULATION 
Combination boats 

Boats of this type are engaged in skipjack pole and line 
fishing from April to September in the coastal and off- 



TABLE 54 
Necetmry refrigerating capacity for fish holds of various 

Refrigerating capacity. Japanese RT 
Volume of storage hold (13,175 BTU/hr. or 3,320 kcal./hr.) 



RaMcamttog capacity for wiow frmfag capadtfet 

Freezing capacity. Refrigerating capacity, Japanese RT 
per 24nrT (13,175 BTU/hr. or 3,320 kcal./hr.) 

Brine Semi air blast Contact 
freezing freezing freezing 


Frozen fish 
storage hold 

530 cu. ft. (15ou. m.) . 1.86 
880 cu. ft. (25 cu. m.) 2.85 
l,770cu. ft ( 50 cu. m.) 4.65 


Other 

fish hold 

0.62 
0.95 

1.55 








(plate freezer) 


2,650 cu. ft. (75 cu. m.) 


5.73 


1.91 


3 ton (6,600 Ib.) 


8 


11 


9 


3,530 cu. ft. (100 cu. m.) 


6,57 


2.19 










4,420 cu. ft. (125 cu. m.) 


7.41 


2.47 


5 ton (1 1,000 Ib.) 


13 


18 


15 


5,300 cu. ft. (ISOcu. m.) 


8.01 


2.67 










6,180 cu. ft (175 cu. m.) 


8.37 


2.79 


10 ton (22,000 Ib.) 


25 


35 


30 


7,060 cu. ft. (200 cu. m.) 8.76 


2.92 



CENTRE UNE SECTION 



A-A SECTION 




WORWNG ROOM PLAN 



FREEZNO 1MXK PLAN 





Fig. 198. Freezing Installation built on the Otteion brine freezing principle 

[236] 



FISH HOLDS TUNA FREEZING 



TABLE 55 
I* far 



3 ton (6,600 Ib.) 

5 ton (11,000 lb.) 

10 ton (22,000 Ib.) 

15 ton (33,000 lb.) 



138ft. (42m.) 
211 ft. ( 64m.) 
329 ft (100m.) 
395 ft. (120 m.) 



Renwks: The table above applies to the evaporation process for 
flooded type with cooled sea water circulation at 16 in. (0.4 m.) 
per second, with cooling coils of 1 1 in. (34 nun.) outside diameter. 



shore waters, and in tuna longline fishing during the 
skipjack off-season. 

As skipjack fishing requires live bait, the tank must be 
constructed so as to keep the bait alive in sea water, this 
being circulated through valves in the bottom of the boat. 
On the homeward voyage, the bait tanks, as well as the 
ice holds on the sides, are used to store the catch. The 
tanks must, therefore, also be insulated. 

The insulation is usually of two or three layers, each 
2 in. (5 1 mm.) thick, sandwiched with soft wood sheathing 
planks. The inside sheathing is made watertight by 
caulking. Fig. 200 shows a typical example of this type 
of fishroom insulation. 

Longliners 

Longiiners used exclusively for tuna do not require live 
bait tanks, so the fish hold is not divided into such small 
compartments as in the combination boats. A compart- 
ment is usually of 2,000 to 3,000 cu. ft. (57 to 85 cu. m.) 
for stowing raw tuna, and sometimes over 7,000 cu. ft. 
(200 cu. m.) when stowing only frozen tuna. 

The insulation is usually of three layers, each 2 in. 
(51 mm.) thick, sandwiched with soft wood sheathing 
planks similar to those used in the combination boat. 
But the watcrtightncss of the inside sheathing is not a 
major consideration. 



TABLE 56 

Nicissary piping lengths for various freezing systems 
Length of pipes 



Freezing 
per 24 



3 ton (6,600 Ib.) 

5 ton (11, 000 lb.) 

10 ton (22,000 lb.) 



Brine 
freezing 

245ft. 
(75 m.) 

410ft. 
(125 m.) 

820ft. 
(250m.) 



; The length of. 

JL- A - * - - *- --J - 

Mir toe anne type, to onne 
per so 

bJatttype,to 
and for 




Contact 
freezing 

260ft. 
(80m.) 

440ft 
(135 m.) 

870ft. 
(265 m.) 

j table applies 
__fl6in.(0.4m.) 

iran.) diam, pipes; for in the semi air- 
ataspeedof6ft8in.< 



Semi air-blast 
freezing 

1,970 ft. 
(600m.) 

3,280ft. 
(1,000m.) 

6,560 ft. 
(2,000 m.) 




IM- 



Fig. 199. Semi air-blast freezing installation for tuna long-liners 

The insulation of the blast freezers is usually of four 
layers, each 2 in. (51 mm.) thick, because of the low 
temperatures. 

Recent trends in insolation materials 

At one time, insulation materials consisted almost 
exclusively of asphalted cork boards, but their use has 
declined since 1953 when new insulation materials were 
introduced. 



TABLE 57 
Necessary pipe fittfe* ratios for fish holds 

Pipe fitting ratio 

Volume offish storage hold Frozen fish Other fish 

storage hold hold 



530 cu. ft. (15cu.m.) 
880 cu. ft. (25 cu. m.) 
1,770 cu. ft. (50 cu. m.) 
2,650 cu. ft. (75 cu. m.) 
3,530 cu. ft. (100 cu. m.) 
4,420 cu. ft. (125 cu. m.) 
5,300 cu. ft. (150cu, m.) 
6,180 cu. ft. (175 cu. m.) 
7,060 cu. ft (200 cu. m.) 



1.21 ft./cu. ft. 0.6 ft./cu, ft. 
(13.00 m./cu. m.) (6.50 ra./cu. m.) 

1.12 ft/cu. ft. 0.56 ft/cu. ft 
(12.00 m./cu. m.) (6.00 m./cu.m.) 



0.91 ft/cw. ft. 
(9.80 m/.cu. m.) 



0.46 ft./cu. ft. 
(4.90 m./cu. m.) 



0.74 ft./cu. ft. 0.37 ft./cu. ft 

(8.00 m./cu. m.) (4.00 m./cu. m.) 

0.65 ft./cu. ft. 0.33 ft/cu. ft. 

(7.00 m./cu. m.) (3.50 m./cu. m.) 

0.58 ft/cu. ft. 0.29 ft/cu. ft. 

(6.20 m./cu. m.) (3.10 m./cu. m.) 

0.52 ft./cu. ft. 0.26 ft./cu. ft. 

(5.60 m./cu, m.) (2.80 m./cu. mj 

0.47 ft/cu. ft, 0.23 ft/cu. ft. 

(5.00 nu/cu. m.) (2.50 OL/CU. m.) 

0.43 ft./cu. ft 0.23 ft/cu. ft.) 

(4.60 m./cu. m.) (2.50 m./cu. m.) 



frtexmg to the ammonia ev 



i.) per i 
method. 



Remarks : Pipe fitting ratios in the above table apply to the i 



using hair-pin type without air circulation and with cooling coil* 
ofl* in. (43 ram.) outside diameter. 



[237] 



FISHING BOATS Oi* THE WORLD: 2 CONSTRUCTION 



The first of the new materials was layer corrugated 
membrane*, made of acetate or Vinyl resin. This has 
been used extensively in tuna boats because of its light 
weight, waterproof quality, easy handling and moderate 
price. But this material could not replace cork boards 
completely because of its comparatively low heat 
capacity, and it is now giving place to the latest new 
materials including foam boards of vinyl or polystyrol 
resin. However, there are now many boats which use a 
combination of these materials. 

Plywood panels art used in some boats for inside 
sheathing, but the sheathing planks formerly used still 
predominate, and a phenol resin coating or polyester 
resin lining is applied to the surface to ensure that they 
are watertight Metal or plastic plating is not yet used in 
Japan. 

As tuna boats are required to store fuel oil in their 
fishrooms on the outward voyage by means of drums or 
plastic bags, every endeavour is being made to ensure 
oiltightness of the inside sheathing, and it is expected 
that the development of synthetic resin will play a big role 
in this problem in the future. 




Fig. 200. Fish hold insulation of 260 GT combination boat 



[238] 



FISH HOLDS DISCUSSION 



DR. . HEEN and OR. R. KREUZER (FAO, Rapporteurs): The 
papers emphasize fundamental points for the design of fishing 
vessels, e.g. the capacity of fish holds, which relate to fishing 
intensity and the time limit for preservation of catches. The 
papers deal particularly with distant water trawlers in Northern 
waters, but they have importance also on fishing boats in 
general. 

Table 45 is based on long experience and carefully con- 
ducted experiments. These figures are valid for ideal condi- 
tions, and it is stated that even three hours on deck may show 
definite changes in the fish, thus indicating the need for rapid 
handling which necessitates care in design of equipment. 

The hold's insulation is dealt with in a comprehensive way 
by MacCallum, who reviews appropriate materials and dimen- 
sions. Insulation can be compensated by the saving of ice. 
The prevention of humidity penetrating the insulation, for 
example, the use of water-proof lining on the warm side of the 
insulation, is unfortunately neglected to a great extent in 
fishing vessels. The need for a proper way of ventilation, 
drainage, etc., is also dealt with in some detail and the paper 
might be regarded as a hand book on the properties of sheathing 
and protective materials. MacCallum correctly refrains from 
advocating the use of one particular material. He only 
describes its properties, and leaves the choice to the naval 
architects, who have to consider the local conditions under 
which the vessel will have to operate. 

Mechanical refrigeration as a supplement to icing is dealt 
with in many of the papers. The limitation lies in the proper- 
ties of air as a heat carrier and its undesired desiccation of the 
fish. 

Shelf-life of the fish may be extended by additional methods 
than chilling. In Eddie's paper reference is made to anti- 
biotics as a possible means of prolonging storage and conse- 
quently longer stay on the fishing grounds, with influence in 
the economy. Some investigators indicate that antibiotics 
may reduce the percentage of spoiled fish, but it will not 
improve quality. There will be a greater quantity of slightly 
inferior fish in the fresh fish markets, and probably a less 
percentage of fish condemned. 

In Slavin's paper, one approach to the problem of freezing 
the catches is described. He makes some comparison with the 
Northern Wave project in the U.K. and it is apparent that there 
is room for compromise between the regular factory freezing 
trawlers and round-fish freezing; it seems also clear that no 
generalization should be aimed at. Each project must be 
evaluated in the light of the working conditions, and mar- 
keting conditions in particular. The solution is, however, not 
merely a technical one. The particular desires and preferences 
of consumers may be a deciding factor in selection of equip- 
ment and methods. 

On Japanese fishing boats, chilled seawater for cooling or 
storing fish is used, as reported by Dofce and Sato. Japanese 
tuna boats, both multi-purpose boats and specialized long- 



liners, are operated for extensive periods in regions with a 
tropical climate, and fish is pre-cooled prior to storing. 

Pre-cooling: About 105 to 315 cu. ft. (3 to 9 cu. m.) with 
coils or plate coolers are used. Unfortunately no figures are 
given about cooling times, although it is obvious that pre- 
cooling in chilled seawater is an excellent method of preserv- 
ing the quality on board fishing vessels, particularly under 
tropical conditions. 

It is stressed that, despite refrigeration techniques, there are 
limits in the handling and preservation of fish on board caused 
by such factors as the working power of the crew, the fishing 
techniques used, the irregularity of the catches, and the 
economic factors as mentioned by Eddie. It is important that 
in the planning and development of fishing boats a close 
collaboration should exist between naval architects, fisheries 
technologists, biologists and experienced people from the trade. 

ICING AND RELATED PROBLEMS 

DR. G. M. DREOSTI (South Africa): He gave a summary of 
various investigations made by the Fishing Industry Research 
Institute (FIRl) into problems connected with the handling 
of fish on trawlers. 

Temperatures in trawler fish holds. Measurements made 
with a 10-point thermocouple with electronic galvanometer 
instrument on board a trawler equipped with an insulated 
fish room, indicated that, while there was little appreciable 
difference in minimum temperatures reached in different parts 
of the fish room, there was an appreciable difference in the 
rate of cooling of fish between the areas of the pounds near 
the hull and those amidships. 

Fish near the hull required an average of about 15 hr. to 
drop to within 1F (iC) of the average minimum temperature 
of 33.8F (+ 1C), while those amidships required an average 
of 3 hr. 

Rates of cooling in ice. A series of experiments in which 
hake, surrounded by crushed ice, were covered by layers of 
either 1 or 5 in. (25 or 125 mm.) of ice, revealed that at an 
ambient temperature of 75F <+ 24Q, the former fish took 
approximately 65 min. to cool from 60 to 35F (+15 to 
-f 1.7C), whereas the latter took about 83 min. to cool 
through the same temperature range. 

At an ambient temperature of 40 to 45F (4 to 7O a 
similar effect was observed, though cooling of the fish was 
slower. For 1 in. (25 mm.) ice the cooling time (60* to 35*F) 
was 1 00 min., but it was 1 30 min. under a 5 in. (125 mm.) layer. 

Thus cooling under 1 in. of ice again took approximately 
80 per cent, of the time under 5 in. of ice. 

These results confirm earlier FIRI observations that cooling 
in ice is considerably faster at room temperature than at 
relatively low ambient temperatures. 

Size aad shape of k*: The size and shape of particles of ice 
used for chilling fish was found to have a profound effect on 



(239] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



TA*LE 58 
a flvtHtey trawler trip to Cape waters 

Ice 



It was also found (hat fh* most econ 






(1) Cooling the fish cargo: 60 tons from 70 



to 3rF (21 to 0C) 

(2) PrcKX>oUng of fish hold: 29x21x12 ft. 6 in. 
(.8 xMx 3.8 m.) from 55 to 40F (12.8 
to4.4Q ..... . 

(3) Preventing heat transfer through outer 
surfaces from warming cargo. 4 in. 
(102 mm.) cork insulation . 

(4) Cooling of air leaking into hold . 

(5) Removal of heat produced by men working 
in hold ...... 



Ib. 

31,700 
2,000 



16,000 
1,000 

600 



Total 51,300 

Say: 26 short tons (23.2 tons) of ice 



kg. 

14,400 
910 

7,250 
450 

270 
23~280 



the rate of chilling* This appears to be due primarily to the 
bridging which occurs with certain types of ice but not with 
others. When blocks of ice were crushed to a particle size 
of about 1 to 1.5 in. (25 to 38 mm.) and two layers of fish 
were packed in this ice, one above the other, the difference in 
time taken to cool from 45 to 35F (7 to 1.7Q for top and 
bottom layers was negligible 81 min. for the bottom layer 
as against 89 min. for the top. No bridging was observed in 
either layer. 

When flake ice was used the difference in rates of cooling 
between bottom and top layers was significant, being 1 15 min. 
for the top layer as against 77 min. for the bottom. The 
bridging in the top layer was about half an inch. No bridging 
was observed in the bottom layer. 

When the same fish were rolled in salt and put in crushed 
ice with some salt sprinkled on the fish, the bottom layer 
cooled faster than when unsalted fish were used (cooling time 
40 min., no bridging observed) but was slower in the top 
layer where bridging now occurred (time 105 min.). With flake 
ice both layers cookd faster than when unsalted fish were used 
and bridging still occurred in the top layer (cooling time 
57 min. in the bottom layer and 93 min. in the top). 

It seems, therefore, that while the rate of cooling is ac- 
celerated by the use of salt on the fish, this acceleration can be 
more than offset by the retardation caused by bridging, which 
in turn is caused by the melting of ice in contact with the salted 
fish. 

Uae of ke on trawlers. Routine records, covering 105 
trawler voyages and approximately 5,000 temperature readings 
during the period August 1954 to March 1955, were studied in 
m attempt to relate the quantity of ice used to the quantity 
of fish caught and its temperature at discharge. 

It was first ascertained from data supplied by the Division 
of Fisheries that there is comparatively little change in air and 
seawater temperatures for winter and summer periods. 

Hie amount of ice melted in a typical trawler during a 
5-<iay trip in Cape waters was calculated according to table 58. 
The calculations illustrated the importance of insulating the 
fish hold; if insulation of only 2 in. (51 mm.) thfcfrw*? had 
been mod, the estimated ovcraH fee consumption would have 
been increased from 26 to 31 short tons. 

It was again found, as noted previously* that lower landing 
temperatures were obtained when the ambient temperature 
was high. 



tl ton of 

ice per 1 ton offish, and that increasing the quantity of ice is 
relatively costly for the temperature advantage gained. Thus, 
for a 60-ton load of fish, 60 tons of ice would be used; of 
this only 26 tons are melted, so that 57 per cent, of the ice 
remains unmelted. 

Re-use of ice. The above figures indicate the desirability 
of salvaging used ice for re-use ashore. Up to 10,000 tons of 
used ice are discarded each year by trawler companies. The 
dirt in the ice consists of scales, flesh and Mood which sink in 
water, and pieces of fat and liver which rise to the surface, 
and bacteria from the fish. 

The best method found of washing ice was to agitate in its 
own weight of fresh water, allow to stand for two minutes, 
lift it out and spray lightly with water to remove floating dirt, 
The yield of washed ice is 65 to 70 per cent. Bacteriological 
tests (total counts and coliform tests) showed that the washed 
ice was as dean as most of the fresh ice (at the time of use) 
from the bacteriological point of view. 

Tests also showed that fish stored as well in washed used ice 
as they did in clean unused ice, whereas in dirty ice the fish 
deteriorated far more rapidly. 

Bulk stacking of ked fish. When fish are bulk stacked, as in 
fish holds or trucks, to a height of 4 to 5 ft. (1.2 to 1.5 m.), 
with ice between layers, and below and on top of the fish, 
there is a certain loss in weight, thought to be due to the 
pressure on the fish; so tests were carried out to find the effect 
of this pressure on the fish. 

Hake were stored in ice and trays containing heavy weights 
were placed on top of the stack of fish and ice. The loss in 
weight after 3 and 7 days was determined. Table 59 (abbre- 
viated) gives the results. 

The bulk density of hake closely packed worked out at 
48 Ib./cu. ft. (770 kg./cu. m.). Using this figure, together with 
those in the above table, the following equation was derived 
graphically between the daily loss of weight of a stack of fish 
and its depth. 

x=0.15-h/100 
where 

x- aver age daily change in weight of hake in a stack 
as a percentage of the original weight of the stack 
and 

h=height of stack of iced fish in inches. 

This equation is based on the assumption that the average 
loss of weight is found by using the pressure on the fish half- 
way down the stack as the average pressure on the fish. Thus 
the average daily loss of weight per cent, in a stack of iced fish 
72 in. (1.83 m.) high =0.5 7 per cent. It will be seen that in 



TABLE 59 
LOM of weight fee 

Equivalent depth of Change in weight of 

Pressure on top cf stack of fish to produce ~ 

fish this average pressure 



Ib./sq.ft. kg.lsq,cm. in. 




11 
172 
194 
297 
332 



0,77 
12.1 
13*6 
20.9 
234 



2.7 
43 
48.5 
74.2 
83 



0*069 

1.1 

1.24 

1J9 

2.11 



After 
3 days 
inice 
+0.53 
+0.11 
-0.54 
-1.07 
-1.05 



After 
7 days 
in ice 
+0*26 
+0.07 
-0.81 



-L28 



1240] 



FISH HOLDS DISCUSSION 



*ingk or double layers of fish {height 1m than 15 in. or 
380 mm.) there is actually a fain In weight according to the 
above formula. Thai is in line with the experimental findings. 

Cutting {Fbking Afewjr, 1951, No. 1975, p. 10) also found 
that the losses in weight of fish at sea were influenced by the 
depth of stacking and his figures are of the same order as the 
above. 

It should be noted that the above equation holds for 
periods of up to seven days but has not been tested for longer 
periods of storage. 

Delay to ktag. It having been noted that a delay of only 
three hours before icing on board was sufficient to cause a 
noticeable effect on the keeping quality of hake, the matter 
was further investigated. 

On a commercial trawling voyage a time study was made of 
22 hauls, ranging from 400 to 8,200 Ib. (180 to 3,700 kg.) of 
fish. 

The time required for hauling up the net varied from about 
20 to about 45 min. The average time spent by fish on deck 
{measured from moment of releasing codend until half the 



white the catch is sorted, cleaned and stacked in ice below 
deck. 

FIRI devised and tested at sea a fish flume which eliminates 
the batch system of cleaning and stowing and gives instead a 
regular flow of fish from the cleaning tables on deck directly 
to the fish hold. The flume runs along the port-side bulwark 
and is fed at the forward end by the deck hose. A small hatch 
amidships admits fish through a chute to the fish hold; the 
water drains away through a grating near this hatch. Pish 
pass down the aluminium chute directly into sorting baskets 
in the hold and are placed in ice within a minute or two of 
cleaning. Fig. 201 shows the fish flume. 

The flume fitted smoothly into the trawler's organization, 
and has many advantages over the existing "basket" system of 
working. Among these advantages are: 

An important reduction about 50 per cent. in the time 
of exposure on deck 

Cooler fish enter the hold 

Protection of fish against trampling, bruising and con- 
tamination on deck 




PQ* 


* 1 

HflMh ' 





Hotoh 




Fig. 201. Sketch of prototype flume for trawlers 



fish was stowed) was 57 min. The maximum time on deck, 
i.e. time till last fish was stowed, was 165 min. (This time was 
taken for a catch of 6,200 Ib., or 3,000 kg.). 

Maximum time on deck, excluding last haul each day was 
98 min. (In the last haul only half the number of workers was 
used). Minimum time on deck, i.e. time till first basket was 
stowed, was less than 22 min. (3,200 Ib., or 1,540 kg., catch). 

It was observed that, while the unavoidable delay in icing 
increased with increasing weight of catch, the rate of cleaning 
the fish also increased in linear relation to the total weight 
cleaned. For instance, when the number of baskets (100 Ib., 
or 45 kg., each) to be cleaned rose from 8 to 51, the number 
of fish cleaned per minute increased from 14 to 31. The 
time for cleaning varied between 3.7 and 0.9 times (averaging 
1.8 times) the time required for stowing. 

There was no relationship between the ratio of cleaning to 
stowing time and the time required for cleaning. 

A trawler Mi Awe. As one of the most important pre- 
cautions for the preservation of trawled fish is to keep its 
temperature as low as possible, the less time it lies on the deck, 
especially during the summer, the better . FIRI investigations 
have shown that the temperature of hake lying on deck in the 
summer sun Can rite to 79 to 81F (26Q after 99 min. 

The summer months coincide at the Cape with the largest 
trawled catches and, as has been shown above, with the 
existing system of working on fish decks, long exposure of the 
fish is unavoidable. Trawling has sometimes to be suspended 



Controllable washing by adjustment of slope of flume and 
by fitting weirs or by variation in water flow 

Work on deck is reduced and contributes to better 
handling by the lessening of fatigue 

Hatches of the fish hold are closed except for the small 
fish hatch, 18 in. (457 mm.) square 

The icing of fish is more carefully done, because fish are 
not "dumped** into the hold in a last-minute rush 

The overall rate of working of the trawler is so greatly 
increased that even with large bags trawling can be 
resumed at once. A catch of 200 baskets was stowed 
away in 125 min. with the flume, whereas with the batch 
system the same crew would have taken at least 5 hr. 
and trawling would have been suspended 

Almost the only disadvantage of the flume is the tendency to 
remove all surface blood from cut-ends and belly cavities, 
thus imparting a livid, grey and white appearance. This 
over-washing of the fi$h can be met, without impairing the 
characteristic extreme cleanliness of the catch, by adjustments 
to the flume and regulation of die water flow, as mentioned 
previously. 

The flume has to be disconnected when the trawler is 
approaching port, but this is speecfitydooe, and the aluminium 
sections can be stowed a way on the engine room casing. The 
flume will stand up to heavy seas and wear and tear. 

Carbon dioxide. Hake, previously chitted, were stoned in 
airtight containers immersed in ice. Concentrations of CO* 



[241 J 



FISHING BOATS 0F THE WOULD: 2 CONSTRUCTION 



varying from 30 to 90 per COOL, were maintained and the fish 
were compared with fish similarly chilled and stored in air. 
The controls kept for 10 days, whereas the CO, treatment 
extended the useful life to 14 days. In all cases, however, the 
flesh was softer than in the controls stored in air, and the 
colour browner, bmng least with 30 per cent, and very dark 
with 90 percent. CO,. 

These findings are in line with those of other workers, and 
the advantage of longer storage life is outweighed by the 
undesirable colour and texture changes produced and by the 
considerable extra expense. 



MR. W, A. MACALLUM (Canada): Reay and Shewan have 
referred to Halifax work on bilgy fish. It has been noted both 
in the laboratory and aboard the boat that iced fish stowed 
against slime soaked wooden boards may spoil very rapidly in 
the areas in contact with the wood. Spoilage of this type has 
been observed within H days of capture in freshly-caught 
eviscerated cod. This was observed in cases where the whole 
fish was reduced in temperature to 32F (0C). It also 
occurred within the same period in cod which were not per- 
mitted to cool below 43F (6.IQ. 

To his knowledge bilgy fish are a cause for concern in a 
few countries and may occur among the catch within a short 
time of stowing. While the effect may wear off in part when 
the unfilleted or filleted fish is exposed to air for a reasonable 
length of time, such an approach to the problem should not 
be tolerated by a firm seriously engaged in the business of 
selling fresh and frozen fillets, since even one bad fish can affect 
the sale of a great many pound of fillets. Thus industry and 
government inspection services should recognize the impor- 
tance of the human factor in the use of ice and in the need for 
properly fitted out fish rooms which cannot harbour bacteria 
in and on materials with which the fish may come in contact. 

Differing interpretations 

MR. G. C. EDDIE (U.K.): Fish is one of the most perishable 
foodstuffs. The naval architect and marine engineers must 
therefore pay particular attention to the design of deck 
equipment and fish holds so as to prevent the rapid develop- 
ment of spoilage. 

Reay's and Shewan* s paper gives an account of the ways in 
which fish is spoilt and lays down broad principles of good 
practice in the design of holds and in the handling of fish, 
especially white-fish in the North Atlantic and Arctic trawl 



The paper represents over thirty years of research and study 
by scientists and engineers. Up to about 1920 the engineers 
and shipbuilders were much further ahead in the develop- 
ment of equipment for preserving all kinds of foodstuffs 
than were the biologists in their knowledge of how the equip- 
ment should be designed and used. This state of affairs led 
to the setting up of a number of national food research 
organizations of which the British Food Investigation was the 
prototype. These establishments were staffed at first mainly 
by bacteriologists and biochemists, and by the 1930*s the 
knowledge they had acquired was sufficient to indicate where 
industrial practices could be improved, and where they must 
be changed. Since World War II engineers and naval archi- 
tects have designed improved chilling and freezing equipment 
and processes on the basis of the scientists' discoveries and the 
time hat now come when the scientific knowledge is again not 
complete enough to allow full understanding of the factors 
affecting Hie operation of die equipment. That Is why die 



paper lays down broad principles only* It is also one of the 
reasons underlying the apparent conflict between the results 
of research in different countries. The biological systems 
involved are so complex that slight changes in practice, in 
size offish or in the amount of fish can afiect the exact manner 
of spoilage* For example, "bilgy" fish referred to by Mac- 
Callum seem to occur much more frequently in Canadian 
vessels than in British. The type of bacteria which will grow 
fastest is controlled by the environment and especially by the 
absence or presence of oxygen and carbon dioxide. Research 
on chilling in the U.K. is now devoted largely to the study of 
the effects of different types of stowage. Another cause of 
different results in different countries are possible differences 
in the physiology of different races of the same species of fish 
and differences in the bacterial flora. 

The engineer and naval architect must beware in inter- 
preting the reported results. For instance, total bacterial 
counts on cod kept in chilled seawater for 1 1 days were lower 
than for similar fish in crushed ice. It was subsequently dis- 
covered, however, that there were more of the types which 
cause spoilage on the chilled seawater fish than on the iced 
fish. 

Results are also difficult to interpret because of different 
standards of judgement. There is no simple way of measur- 
ing the quality or freshness of a fish. Some aspects are more 
important in one country than in another. In the U.K., the 
standard used is "equivalent to x days in ice under ideal 
conditions 9 * as judged by organoleptic and chemical tests and 
bacterial counts. A new method of preservation may be 
judged a success in one country and a failure in another. 

This also depends on how well the orthodox method is 
applied in practice. Thus the reported success of chilled sea- 
water in some parts of Canada and the less encouraging 
results in parts of the U.K. might possibly be explained not 
only by biological factors but also by the fact that the average 
temperature of normally iced fish is higher in the area where 
the success was reported. Nevertheless the broad principles 
of good preservation are clear. The fish must be well gutted 
and washed, cooled as soon as possible and kept cool. It 
must not be handled roughly or more frequently than neces- 
sary. The only successful chilling media are ice and chilled 
seawater. If ice is used, the design of the hold and its equip- 
ment must be such that the ice is allowed to melt. Sufficient 
care must be taken to prevent fish from touching each other 
or the surfaces of the hold. The hold, equipment and ice must 
be kept very clean in the ordinary sense but it seems that 
further improvements in keeping offish cannot be gained short 
of achieving the sterility of the surgeon's operating table. 
The most important single factors are temperature and time. 

The naval architect should, in designing decks and holds, 
bear in mind the principles laid down in Reay's and Shewan's 
paper. It does not attempt to suggest detailed designs but it is 
hoped it will form a useful source of background information 
when considering papers such as the one by MacCallum. 

MR. J. PMOSKIB (Canada): Reay and Shewan have produced 
the very interesting and useful table 45. Because fishing craft 
already cost so much would they recommend freezing at sea 
or using refrigerated seawater in pieferenoe to icing for vessels 
under 70 ft (21.4 m.) LOA and which do not stay at sea for 
very long periods? Ta We 60 indicates the days at sea in fishing 



LOA. 

His own observations and conchnkms so far indicate that 
the introduction of the more costly methods of preserving fish 



[242J 



FISH HOLDS DISCUSSION 



TABLE 60 



Area 

Type of boat 



Nova Scotia 
Longiiner 



Newfoundland 
Trawler 



BayofFundy 
Trawler 



New Brunswick 
Trawler 



Percentage of total days at sea 



Nova Scotia 
Trawler 



Trips made which were 










1 day at left 41.1 


19.1 


27.8 


1.3 


7.8 


2 days at tea 






16,0 


6.4 


20.3 


10.9 


9.8 


"* M t 






10.0 


6.4 


25.6 


29.2 


2.0 


^ ft It tl 






7.4 


22.0 


19.5 


38.9 


6.3 


J ,4 M 






5.0 


22.7 


6.8 


16.7 


8.8 


6 days and over at sea 




20.5 


23.4 





3.0 


65.3 


Average days at sea per trip 


3.6 


4.1 


1.7 


3.7 


6.3 


Average landings per trip (tons) 6.4 


12.1 


8.1 


12.9 


14.7 



at sea would reduce the profitability of operations under the 
existing cost-price relationships. 

Better handling needed 

COMMANDER M. B. F. RANKEN (U.K.): We should not lose 
sight of the paramount need to improve shore facilities for 
handling the fish and for processing, distributing and selling it. 

Handling. Current practice at most fish docks for unload- 
ing fish is so primitive and unhygienic that there would appear 
to be little point in improving the treatment of fresh fish on 
board fishing vessels until it can be properly handled after- 
wards. Perhaps boxing on board offers a solution in conjunc- 
tion with paternoster or other type hoists and conveyors, or, 
for wet fish only, the fish pumps used in some ports in the 
U.S.A. might be applied elsewhere at least for small fish. 

If fish is to be handled efficiently and hygenically on shore 
it seems essential to suppress the fish auction markets as 
known today and to handle the fish right from catching to 
the fishmonger's shop through properly integrated organiza- 
tions fully responsible for every step. This is already being 
done to some extent by a few big companies in the U.K., 
Greece and other countries and is presumably a salient point 
in the handling of fish in the U.S.S.R. The day should not be 
so very far off when fish, or at least frozen fish, can be handled 
right from the time it is sorted on board the vessel until the 
housewife begins to prepare it for cooking, without any 
contact with human hands (or feet). 

Cold tores. Most cold stores currently being built for 
frozen fish in the U.K. are designed for a holding temperature 
of ~20F (-29C). Many have already been completed but 
many more are needed not only at the ports but also at 
distribution centres all over the country. Similar trends exist 
in other countries though in some cases the temperatures 
being used at present are too high. 

Transport In the U.K. there is relatively little refrigerated 
land transport at present but large numbers of road and rail 
vehicles and/or containers will be needed capable of trans- 
porting frozen fish at -20F (-29C). Similar requirements 
exist in other countries. Some, like the U.S.A., are already 
well provided, although temperatures in depots, ships and 
shops are generally far too high. 

Ice. Much has been said, about the importance of toe on 
board fishing vessels particularly of conventional types, 
though it is also important for the buffer storage and chilling 
of fish before processing in many factory ships. However, 



we have inevitably taken for granted the supply of ice at the 
ports or on board ship. 

Factory ships must make their own ice and various designs 
of so-called flake-ice machines are available for this purpose. 
In some cases it has been found necessary to make this ice 
from salt water, but this is not recommended as salt water 
ice freezes at too low a temperature which may damage the 
fish, the temperature rises as it melts, and a strong brine is 
formed which may penetrate the fish and give it an unpleasant 
flavour and poor appearance. Where it is impracticable to 
provide fresh water either from tanks or from a distilling 
plant, the objections to salt water ioe may often be obviated 
by the use of chilled seawater circulated through fish pre- 
ceding tanks. Such chilling plants are usually more eco- 
nomical of power and less costly than ice-making plants. 

However, apart from a few using chilled seawater, all 
vessels landing wet fish require large quantities of ice in pro- 
portions as high as half a ton of ice per ton of fish to be 
cooled. As it takes as much as 5 to 6 BHP on the freezing 
compressor to produce one ton of ice per day, quite apart 
from the size of the apparatus, it is obviously impracticable 
in most cases to make this ice on board ship and it must 
therefore be obtained from shore. This point needs emphasis 
as many enquiries have been received in recent years for plants 
to be installed in very small fishing vessels where the power 
required for the ice-maker would often be greater than that 
of the main engine. 

Ice is a cheap commodity in the large U.K. ports like 
Grimsby, Hull and Flcetwood where the cost is as low as 
17s. ($2.4) a ton, but in many smaller ports supplies have to be 
carried considerable distances from the large ioe factories and 
some British near-water fishermen have to pay more than 
4 4s. ($11.8) per ton. Conditions are no doubt similar in 
many other countries, but they are far worse in some tropical 
ones where there is not only a shortage of ice but abo of 
clean fresh water from which to make it. 

Until recently plants suitable for use in these small ports 
have not been obtainable but today "rapid-ice" and "flake- 
ice" plants are available in small sizes, the latter even below 
one ton per day, and flake-toe at any rate appears to be com- 
petitive in price with the crushed ice produced at the larger 
ports, though rapid-ice is at present somewhat more expensive. 



COMMODORE D. D. SILVA (Portugal): Portuguese trawta 
(without cooling coils in the fish holds) use about one ton of 



[243] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



TABLE 61 



Material Mahogany 
Sq. ft. Sq. m. 
per per 
Imp. gal. litre 


Spruce Douglas fir 
Sq.ft. Sq. m. Sq.ft. Sq. m. 
per per per per 
Imp. gal. litre Imp. gal. Gtrc 


Two-pack . 
2nd coat 


555 
755 


11.3 
15.4 


682 

775 


13.9 
118 


530 
740 


10.8 
15.1 


Shftlhic 
2nd coat 


710 

978 


14.5 
20.0 


980 

885 


20.0 
18.1 


755 
935 


15.4 
19.1 


White paint . 
2nd coat 


575 
640 


11.8 
13.1 


665 
690 


13.6 
14.1 


665 
643 


13.6 
111 



ice per ton of fish. One ton of ice actually in the hold will 
conserve more than one ton of fish since a loss of 10 to 15 per 
cent, in volume occurs by melting on the trip out to the 
fishing grounds. 

It is well to note that the fish hold must be arranged with 
divisions as small as possible and temperatures obtained 
should not be lower than 30 to 28 F ( - 1 to - 2Q . 

Cooling coils under the deck had not proved to be of 
advantage, but he emphasized the great advantage of coils 
fitted on bulkheads and partitions, sides and bottom. With 
die latter considerable quantities of ice can be saved (about 
J to D and practice seems to indicate that the fish caught 
during die first days of a long fishing trip arrives in better 
condition than if kept only in ice. 

However, he agreed with Rcay and Shewan that fish kept 
only in ice, in a hold without cooling coils, is usually of better 
quality than the one kept in a hold with them, provided it is 
kept no longer than 10 to 12 days. 

Portuguese distant-water trawlers are very often at sea 
considerably longer than that and the fish has to be stowed 
for as long as 15 days; then the slightly negative temperature 
maintained by the coils noticeably slows down the progress 
of protein decomposition provoked by bacteria in the fish. 

The disadvantages resulting from absence of ice and conse- 
quently of humidity on the surface of the fish placed near the 
cooling sources, the partial freezing of a portion of fish placed 
practically against the coils are in his opinion compensated 
for by the bettor condition of the bulk of the fish. 

Portugal had for many years been dedicating the greatest 
attention to the problems of handling and conserving the fish 
on board. In fact, the Fisheries Organization had distributed 
among the crews literature on the subject, advising on the best 
methods of handling and keeping the catch. 

MR. J. W. SLA YIN (U.S.A.): He agreed with Reay and Shewan 
in the need for cleanliness on the vessel, even though scien- 
tific evidence as to its exact value was quite confusing. Within 



TABLE 62 



Dryiag 



Two-pack 


Shellac 


White paint 


Wood 


1st 


2nd 


1st 


2nd 


1st 


2nd 




coat 


coat 


coat 


coat 


coat 


coat 


Hours 


Minutes 


Hours 


Mahogany . 
Spruce 
Douglas fir 


. 3 
. 3 
, 3 


3 
3 
3 


30 
30 
30 


30 
30 
30 


if 


if 



die past year they had investigated the ute of chlorinated 
eawater on trawlers in U.S.A. Their observations showed 
that seawater containing about 60 p.p,m. of free chlorine was 
eflbctive in washing the eviscerated fish, prior to icing, and in 
washing the vessel's hold in port. Also, the chlorinating 
equipment operated satisfactorily on the vessel and required 
little attention. As a result of these tests chlorinating equip- 
ment has been installed on ten Boston trawlers. 

Reay's and Shewan's suggestion about the need for larger 
hatch openings to permit better discharging Of the fish is a 
good one. This should be given serious consideration hi the 
design of new trawlers. 

The ice-fish ratio of 1 to 1 for British trawlers seems high. 
This means that boats landing 200 tons of fish would have to 
carry at least 225 tons of ice to make up for the melting. They 
have found a ratio of 1 part ice to 3 parts fish to be quite 
satisfactory. 

There may be some practical problems in storing and 
handling fish if the hold shelving is only 18 in. (0.46 m.) 
high. In the U.S.A. they have found a shelving height of 
3 to 3.5 ft. (0.9 to 1.1 m.) to be satisfactory for commercial 
practice. 

In tests conducted on the Delaware they observed that 
properly iced haddock and cod had a maximum acceptable 
iced storage period of only 12 days. Similar results have also 



TABLE 63 
Drying times of points In cold temperatures 



Wood 

Mahogany . 
Spruce 
Douglas fir 


Two pack 
1st 2nd 
coat coat 
Hours 
. 7 16 
. 7 16 
. 7 16 


Shellac 
1st 2nd 
coat coat 
Hours 

\ 1 


White paint 
1st 2nd 
coat coat 
Hours 
5 16 
5 16 
5 16 



been reported by Canadian workers. It seems, however, the 
storage period for British landed fish is from two to three 
days longer. Is this because in the U.S.A. and Canada a 
slightly milder product is required than in England, where the 
vessels have to stay out from 1 8 to 20 days ? 

DESIGN OF FISH HOLDS 

MR. ELLIS PRUCHNIE (U.K.): MacCallum's paper, section 
Coatings and Linings, p. 216, mentioned three types of paints : 

Hard-drying phenolic resin modified with specially for- 
mulated oil alkyd 

9 Shellac paints 

Plastic base paints requiring the addition of a catalyst 
As MacCallum very clearly points out, plastic based paints, 

requiring the addition of a catalyst, need care in application 
if they are to provide the maximum protection of which they 
are capable. Hiat they are far superior to other types of pro- 
tective coatings, and therefore well worth the extra care in 
application, will be shown in the following results obtained 
from tests. 

Three coatings were used: white fish mom paint (hard 
drying phenolic resin modified type), shellac (an uapigmented, 
deep orange coloured shellac varnish) and a two-pack dear 
varnish (being a synthetic resin based varnish, chemically 
dried by adding an equal volume of suitably formulated 



1*4] 



FISH HOLDS DISCUSSION 




Fig. 202. Abrasion test machine for testing points 

catalyst). All the tests were carried out on mahogany, spruce 
and Douglas fir to illustrate different rates of absorption. 

Spreading capacities. Two coats of paint were applied to 
the three different woods and the spreading capacity deter- 
mined by subtracting the weight of brush, paints and con- 
tainer after application from the previous weight. Table 61 
shows the results. 

Drying times. The materials under test were applied to an 
area 12x12 in. (0.3 x 0.3 m.) on the different woods. Using a 

1 in. (25 mm.) brush, panels were coated with 2 to 3 oz. per 
sq. yd. (35 to 50 g. per sq. m.) with the white paint, 1 to 1} oz. 
per sq. yd. (35 to 50 g. per sq. m.) with the shellac and 1 to 

2 oz. per sq. yd. (50 to 70 g. per sq. m.) with the two-pack 
material. Normal room temperature was maintained through- 
out the drying period, which was 60 to 70F (15 to 21C), 
and the relative humidity was 60 to 70 per cent. Table 62 
gives the results. 

A set of results showing longer drying times at lower 
temperatures have also been recorded. In a specially con- 
structed cabinet showing an internal temperature varying from 
48 to 54F (8.9 to 12.8Q, with a relative humidity of 70 to 
80 per cent., the results are given in table 63. 

Abrasion tests were carried out on twice-coated panels. 
The panels measured 6 x 4 x i in. (150 x 1 00 x 6.35 mm.) to fit 
the "REL" abrasion test apparatus, fig. 202, which records 
the number of complete oscillations of the abrasion brush 
before signs of film wear appear. The brush had nylon 
bristles and had an applied load of 0.66 Ib. (300 g.). During 
tests the surfaces were continually wetted with an 0.5 per cent. 




Flf.2Q3. R*s*toofabnuto*t*stt. Tb whit* JM room varnbh fa 



solution of * commercially obtainable wetting agent, non 
ionic, polyethylene oxide type. Hie results shown in fig. 203 
were as follows: 

Two-pack: 225,000 strokes with no sign of wear 
Shellac: 8,000 strokes worn through 

White paint; 12,000 strokes worn through 
Water absorption tests. Wooden panels, 6x4xf in,, 
were given two coats of the materials under tet The ends 
were completriy sealed off by dipping them in a tray of molten 
wax, leaving the absorption test areas equal on each panel 
The uncoated control panels were similarly sealed on the ends. 
All the panels were totally immersed in water, and each was 
weighed before and after testing so that absorption figures, 
expressed as a percentage, could be calculated. The tabie 64 
and fig. 204 illustrate the greater protective power of the two- 
pack varnish over the other two materials. 




Fig. 204. Result of water absorption tests 

Resistance to chemical solutions. Wooden panel surfaces 
had two coats of the material under test, but to ensure adequate 
sealing the ends had four coats. Seven days after coating, the 
panels were half immersed in the test solutions which were: 

(a) 0.5 per cent, ammonia 

(b) 2.0 per cent, caustic soda 

The effects of the chemicals on the paints can be seen from 
fig. 205 and 206, and were as follows: 
Shellac: 0.5 per cent, ammonia complete removal 

within 24 hours 

2.0 per cent, caustic soda complete removal 

within 24 hours 



TABLE 64 

. f .-M^fcjl M-mfa^-ii tij_ 

I vi wutPU prtPWdBB WMR 

5 7 10 14 15 21 

days days days days days days 

Douglas fir (uncoated) . 26 33 40 

Mahogany (uncoated) . 20 30 40 

Spruce (uncoated) . 25 30 35 

Shellac on mahogany . 8 10 12 15 

White paint on mahogany 5 7 9 11 
Two-pack on mahogany. 1 124 



[245] 



FISHING BOATS OP THE WORLD: 2 - CONSTRUCTION 




Fif. 205. Resistance to OJ per cent, ammonia. Both the white fish 

room paint and shellac have broken down whilst no breakdown is 

visible on the two-pack panel 



Whhc paint: 0.5 per cent, ammonia complete removal 

within 24 hours 

2.0 per cent, caustic soda complete removal 

within 24 hours 
Two-pack: 0.5 per cent, ammonia unaffected after 

immersion for 7 days 

2.0 per cent, caustic soda unaffected after 

immersion for 7 days 

Practical tests at sea. The laboratory results obtained were 
borne out under actual working conditions at sea. Apart from 
these, however, other observations were made which, although 
they emphasized the distinct advantages which the two-pack 
varnish had over the other two, also showed that extra care 
had to be taken to ensure success. In the case of new and 
unpainted woodwork, little difficulty was experienced pro- 
viding that a reasonable drying time was allowed between coats 
and that the wood was also reasonably dry. Trouble can be 
experienced on previously painted wood unless extreme care is 
taken. It is essential that all the loose flaking material of the 
previous coating be removed and that adequate care is taken 
to dry out the wood. This latter is not always easy to accom- 
plish as most owners cannot afford the time necessary to dry a 
fish room properly. Trouble can also occur on surfaces which 
have previously been treated with a paint that contained a 
large percentage of oil. Two-pack varnishes usually contain 
''searching" solvents and although the surface of the previous 
coating may seem quite sound, the solvents in the two-pack 
varnish will seep through and soften the film thereby reducing 
the adhesive properties of the new paint which leads to an 
early breakdown and "peeling". Temperature had a greater 
effect on the drying time of the two-pack varnish than on the 
other tested paints and it was found that the film would not 
cure below 45F (7C). 

Conclusion. Two-pack varnishes, consisting of a varnish 
base and catalyst, are much more durable than conventional 
fish room protective paints due mainly to their hardness of 
finish, which is the nearest approach an air-drying material 
can get to a stoved finish. The varnish tested showed not only 
resistance to chemical and bacterial attack but also exhibited 
properties of pliability and a lack of brittleness. The smooth 
hard surface of this varnish does not afford an easy key for 
fish slime or other foreign matter and so is easily kept clean. 
Detergents normally used for cleaning have no effect on it. 
It is, of course, true that they are more expensive than con- 
ventional finishes and that extra care is needed during applica- 
tion, but practical results have shown that they protect the 
woodwork longer than other previously used paints and that 
they reduce the risk of bacterial contamination. Over one 



hundred vessels in the U.K. and elsewhere have now been 
treated In this manner and bear conclusive evidence of the test 
results which have been described. 



MR. F. STRAKOSCH (Italy): Ice has been and is still the most 
widely used medium for the preservation offish. It represents 
cold in Hs most handy, concentrated and economical form. 
Mechanical refrigeration, as applied to fish holds, is a welcome 
complement to the basic preserver, known for very many 
years. It is reported that the old Romans used snow or 
natural ice to bring fish to the capital from far-away places. 

The reason for its wide use is that ice when it freezes 
accumulates a considerable amount of heat 1 45 BTU per Ib. 
(80 kcal. per kg.) which, when it melts, is released to the 
surrounding medium. This chilling potential can be directed 
at the user's discretion on to large or small surfaces to reduce 
the temperature of organic matter to a degree at which 
decomposition is almost inhibited. 

The product of the operation is water, to the extent of some 
660 Ib. (300 kg.) per ton of fish treated, and may thus amount 
to a good many tons of water to be disposed of. 

As known, the catch, after sorting, is stowed with ice, either 
in compartments of the fish holds divided by wooden or metal 
partitions and covers, or in boxes. 

With both methods water is released from the stowed mass 
and drips underneath, finding its way to the bilges or a sump. 
Thus the liquid runs over a large portion of the insulation and 
some of it penetrates the insulating material, impairing its 
heat repelling capacity. The bottom of the hold is particularly 
affected in this way. 

In colder regions insulation is frequently omitted from fish 
hold floors, but the floor is covered with wood planking which 
easily absorbs moisture. This practice of having uninsulated 
floors would be objectionable in warmer climates, since it is 
obvious that heat exchange is most active on such surfaces, 
the heat from the bilge being on the lower side and cold on 
the upper surface. By insulating a fish hold floor this heat 
exchange is considerably reduced. 

But only by keeping the insulated surfaces dry can their 
heat repelling property be conveniently maintained. To attain 
this goal, it is necessary carefully to water-proof the inner side 
of all boundary surfaces of the fish hold, and to do this tongue- 
and groove planking is usually fitted over the layers of cork 
or other material and painted. Sometimes a layer of tarred 
cartoon is inserted between cork and planking; in other 
instances a light alloy sheathing is used. 




Fig. 206, Resistance to 2 per cent, caustic soda. Both the white fish 

room paint and skttiac have broken down, whilst no breakdown ft 

vWbb on the two-pack pond 



1246] 



FISH HOLDS DISCUSSION 



None of theae systems, however, is completely successful, 
as small leak* can hardly be avoided; the best results have been 
obtained with a sheathing of zinc plates screwed or nailed to 
the tongue-and-groove boards and carefully soldered at all 
joints and on the screw or nail heads, so as to be thoroughly 
waterproof. 

The floor sheathing should continue through the framing 
of all manhole covers so as to avoid penetration of water 
through the connections of such frames to the floor planking 
and insulation. 

The efficient waterproofing of the inner side of insulations 
will lead to an all-over improvement of insulating efficiency, 
which in turn leads to better preservation, economy of ice, etc. 

Galvanized iron sheets are not recommended because rust 
may make subsequent soldering for upkeep too difficult. 
Synthetic resin coating is reported to have been applied to fish 
hold surfaces with good results but appears to be still in the 
experimental stage. Developments in this field should be 
closely watched, especially in respect of subsequent upkeep 
to preserve the waterproof qualities. 

These matters, important in any climate, are particularly 
serious with high ambient temperatures, with the increase of 
temperature differentials and, thus, of the quantity of water 
that has to be dealt with. 

The attention of builders is therefore especially called to the 
proper design, installation and maintenance of the insulation 
in fish holds to ensure that it is heat as well as water repellent. 

As stated, the greatest heat exchange occurs on the floors 
of fish holds; so for this reason an increase in the thickness of 
insulation on such surfaces by 1 in. (25 mm.) or more is 
recommended. 

Another difficulty in the operation of fish holds whatever 
the type of refrigeration used (ice only or ice plus refrigeration) 
is the external temperature fluctuation. Air warmer than 
that in the fish hold and the catch packed there enters in large 
volumes every time the hatch door is opened. As a result, a 
large portion of the fish room vapour condenses on the surface 
of the stowed fish and the general temperature inside also 
rises. Both factors favour the growth of microbes and thus 
deterioration, even of the more delicate internal parts. 

Refrigeration coils may worsen the situation because many 
fishermen run the plant with hatches or doors open with the 
mistaken idea that the fish will be better preserved and 
dripping from the overhead coils is avoided. 

Temperature fluctuations can be reduced to a considerable 
extent by taking special care in the design of spaces intended 
for fish stowage and also the handling of the catch. The catch, 
after each haul, is put in the fish hold through its openings and 
thus warm air has full access for periods varying between 
10 and 30 min. or more. This happens many times a day 
during fishing so it will be easily understood that the cumula- 
tive adverse effect on temperature and moisture conditions is 
great. To overcome these troubles, it is suggested that an 
insulated and if the boat has refrigerating equipment- 
cooled packaging room be arranged where all the operations 
previous to storage are done so that the fish hold itself is 
opened only for shorter periods and perhaps at longer inter* 
vals. When fish is packed into cases with ice, the whole opera- 
tion can be done in the pftpk*r*g room *&d the cases toft 
there until the next haul. This would have the further ad van- 
tage that a product of uniform temperature would be stored 
in the fish bold whore no or very little melting of ice would 
be required to reduce it to the ri^t temperature. This method 
hu^vta excellent iwults in practice. Obviously it is advisable 
to dote the door of the packaging room and keep it shut as 



soon as the catch Is placed therein, to the extent, of course, 
that the men working in the room have fresh air. 

But matters are not as simple as that when large catche* 
are stowed in bulk. Nevertheless, the ingenuity of designer* 
and the skill of skippers and fishermen will no doubt overcome 
the difficulties. 

On the refrigerating equipment itself, a few basic recom- 
mendations may be of use. Small or medium sized fishing: 
boats can hardly afford to have a refrigerating mechanic 
among their crew; therefore the plant and its layout should be 
as simple as possible and easily accessible, so that the normal 
engine room personnel can handle it. To achieve this, these 
are the main points to bear in mind : automatic working as far 
as possible; standard parts for easy replacements; frequent 
inspection by specialists, preferably before each voyage; good 
and even distribution of cooling coils on the Jiqnilated surfaces 
to approach the conditions obtained in "jacketed holds"; 
setting the thermostat to maintain a temperature of, say, 
30F (- 1C) in fish holds, and 10 to 14F (6 to 8Q more in 
the packaging rooms, the thermostat controls to be outside 
the fish room. 

When it is not practicable to pack and pre-cool the fish 
outside the final store room, measures should be taken to 
prevent melting water dripping on to the lower layers, and to 
direct the water away from the fish. Packing the first catches 
in closed, insulated, light alloy containers has given good 
results in trials. 

Finally, it must be remembered that the water produced 
from the ice surrounding fresh fish gets loaded with organic 
matter and becomes a fairly concentrated bacterial broth 
likely to carry contamination anywhere it penetrates. 

MR. J. W. SLAVTN (U.S.A.): MacCallum's suggestion to 
arrange the stanchions so as to permit interchangeability of 
the pen boards is a good one. This is sorely needed in many 
fishing trawlers. 

All coatings used in a fish hold should of course be non- 
toxic, otherwise contamination of the fish may result. It is 
essential that the fish hold be thoroughly dried out before 
applying existing commercially available coating compounds. 
A coating that can be applied to a moist or only partially 
dried surface is badly needed to prevent excessive loss of tune 
due to drying out of the hold. He would like to learn if 
MacCallum has found any coating materials that can be 
applied satisfactorily without drying out the fish hold. 

In regard to the use of metal screens in die fish hold, it 
would seem that such screens would be very difficult to dean. 
Specifically, he would like to learn if MacCallum has ob- 
served any difficulty in cleaning these screens. MacCallum's 
paper will be of considerable value to naval architects in 
designing and fabricating fish holds. 

COMPARISON OF FREEZING INSTALLATIONS 

MR. G. C EDDIE (U.K.): At the first Congress he had said, 
as does Slavin now, that the problems of freezing at sea are 
different for each fishery and different solutions will apply. 
Comparison of the Delaware and Northern Wave will be 
useful only if that is borne in mind. 

This is particularly true when discussing the handling, pro- 
cessing and quality of the products and it is quite obvious that 
Slavin did not see for himself the products from the Northern 
Wave: the standard of quality aimed at in this experiment was 
very high for reasons which are given below and the assess- 
ment of the Northern Wave fish is therefore not directly 
comparable with that of the Delaware flab. 



[247] 



FISHING BOATS OF THE WORtD: 2 CONSTRUCTION 



Before discussing the different standards further, it is 
necessary to take exertion to fee statement in Slavin's 
summary, that the texture of the M>rrA*r fftn* fish was soft 
and the fish difficult to fillet This it most misleading. Some 
of the fish was soft for biological reasons; it is true that, in 
general, slightly more care is required in filleting than with 
good-quality toed fish hut sea-frozen fish is by no means 
difficult to fillet. Much sea-frozen fish is of a very firm 
texture. 

Reports on the quality of fish as landed from the trawler in 
the U.K. and in the U.S.A. cannot be compared without 
examining the standards of comparison and taking into 
account the ultimate use of the product. In general, the 
.quality of iced fish after a given number of days on the fishing 
vessel seems to be higher in the U.K. than on the western sea- 
board of the Atlantic, partly because of the more liberal use of 
ice, a mean fish temperature of below 32F (-0C) being usual 
on large British trawlers. The standard against which sea- 
frozen fish will be compared by the practical man is therefore 
in this sense higher, and the Northern Wave report must be 
read accordingly. More important, perhaps, is the fact that 
Northern Wave fish were produced to compete with iced fish 
for all purposes that is, the fish were presented to the ulti- 
mate consumer as whole fish, steaks and fillets in the wet 
condition, as smoked fish or smoked fillets, as well as in the 
form of frozen fillets, fish fingers and so on. The appearance 
of the thawed whole fish is therefore of importance. Moreover, 
die most stringent and severe test of freezing and cold storage 
practice is to split or fillet the thawed fish and smoke it High- 
grade products according to these very exacting criteria simply 
cannot be made by brine immersion freezing and cold storage 
at 0F ( 18Q. Slavin is not correct in implying that only 
plate-frozen fish must be stored at -20F (-29C) for 
maximum quality. This applies to all frozen fish, and the 
point is generally accepted in the U.K. where for many 
reasons, which need not be given here, most frozen fish stores 
operate at -20F (-29 Q, regardless of the type of freezing 
operation or product. 

Where the product is frozen fillet in consumer packs some 
relaxation of these temperature requirements would, in British 
opinion, be possible for short periods of storage, say, no more 
than four months at -5F (-2PC). Frozen fillet of reason- 
able quality can be produced from fish up to ten days in ice 
or more, but if the appearance of the thawed fish is important 
or it is to be smoked then the fish must be frozen within three 
days of catching and stored at -20F (-29C). 

There is, therefore, a considerable difference between the 
type of product and the standards of judgment in the Delaware 
and Northern Wave experiments. 

No difficulties are experienced with plate-freezing fish prior 
to the onset of rigor mortis except in a small percentage of 
cases and trouble can be avoided completely provided that the* 
fish are stored for a period of several weeks. 

Because storage at - 20F (- 29Q allows fish to be kept in 
ice for as much as three days before freezing, a considerable 
reduction in the size and capital cost of the freezing plant is 
possflrie as compared with what would otherwise be necessary, 
in the latest design, based upon the Northern Wave, the 
freezer throughput is 200 kits (12.7 ton) per day equivalent 
<1 kit equals 140 Ib. or 63.5 kg.) but with a low temperature 
hold limited to 1,200 Idts (75 tons) equivalent this allows 
the f reeaser to deal with an average tste of catch of 400 kits 
{25.4 ton) par day, and a peak on any one day of 800 kits 
(51 too). This is very heavy cod fishing indeed. The ro- 
handling of the fish from the wet fish hold to freezer is done 



by the freezer hand who is not otherwise fully employed. 
The freezing operation is carried on entirely below decks* 
With this system, therefore, the freezer throughput can be as 
low as one-quarter of the maximum catch that can be expected 
in a 24-hr, period. 

The ratio of fish in iced stowage to storage space in a 
British trawler may be 32 Ib./cu. ft. (510 kg./cu. m.) or as low 
as 14 Ib./cu. ft. (224 kg./cu. m.) depending upon die method 
of stowage. The latter figure refers to "shotted" fish (see 
Reay's and Shewan's paper). 

Regarding space occupied by freezing plant, the Northern 
Wave was for a number of reasons fitted with a plant larger 
than that which was necessary or desirable. The result was 
that on average no extension of voyage was possible. There 
seems little merit in subjecting more fish than necessary to 
the expensive freezing operation, the proportion of frozen 
fish should therefore be decided either by the limitations of 
crushed ice or by considerations of seasonal fluctuation in 
supply and demand. The higher proportion of frozen fish 
on the Delaware was no doubt due to the compactness of the 
plant, arising from the smaller size of the fish which in turn 
allows full advantage to be taken of the high rates of heat 
transfer possible in brine immersion freezing. The latest 
design of plant based on the Northern Wave, however, has a 
much improved throughput per unit of space occupied 
about 40 per cent, higher so that the throughputs mentioned 
above can be achieved in a freezer disposed athwartships, this 
saving yet more space as compared with the Northern Wave. 

Some figures regarding hold size and utilization on British 
distant-water trawlers were given in his own paper. 

The costs of unloading the frozen fish from the Northern 
Wave were rather less than for wet fish despite the makeshift 
apparatus used. 

Water-thawing is not acceptable for large cod where appear- 
ance and texture is important, although thawing may be 
started in this way if under the control of an expert. 

Development of compact dialectric thawing plant is pro- 
ceeding, but it must be pointed out that the costs of air 
thawing have been taken into account in assessing the eco- 
nomics of freezing trawlers of the type described in the paper 
referred to above (see also Hunter and Eddie, 1959). 

Quality aspects have been discussed above. Slavin is mis- 
taken about the texture in cold-smoked fish; it is most 
important. 

Regarding economics, it is to be noted that the Delaware 
experiment related to a fishery which would be viewed in the 
U.K. as a middle-water fishery rather than distant-water. 
Vessels generally under 140 ft. (42.7 m.) making 10 to 14 day 
trips can land fish in an acceptable condition without freezing, 
having regard to the more liberal use of ice, and some of the 
catch is fit for freezing on shore even by the highest standards. 
The advantages of freezing are much clearer in the case of the 
European distant-water fishery. As pointed out in his own 
paper, the limitations of crushed ice have resulted in the con- 
struction of ships with engines developing more than twice 
as much power as required in the trawling condition, and 
operating at speeds where the power is varying as the seventh 
index of the speed. Better preservation reduces the need for 
speed, and smaller engines and bunkers release more space 
for freezing plant (see also Hunter and Eddie, 1959). 

Regarding Slavin's overall evaluation, it is not agreed that 
freezing at sea need result in slower handling on board, 
although it may require one or two extra men. The economic 
advantage of the ability to operate at lower speeds and powers, 
than at present necessary in some fisheries, has to be added to 



FISH HOLDS DISCUSSION 



those h*ed by Slavin, The advantage to owner and crew of 
maximum utilization of capacity on every trip is, of course, 
that the trawler will spend more days in a year on the fishing 
grounds and fewer in running to and from the grounds. This 
in turn implies capital savings in terms of the number of 
vessels required to produce a given quantity of edible fish. 

MR. T. MITSUI (Japan): He requested clarification on the 
following points regarding Slavin's paper: 

Which method was adopted to freeze the catches: was 
the brine stirred by propellers, pumps, etc., or were the 
baskets with the catch moved in the brine? 

How was the appearance of the fish when frozen by that 
method? In Japan appearance was determining the 
market value of the fish 

What was the exact meaning of "buffer" storage pen, and 
what are the details of the plate-freezing unit (including 
the weight of one charge)? 

Preference for iced fish 

SIR FRED PARKES (U.K.) : One of his 190ft. (58 m.) super trawlers 
was equipped with a refrigeration plant and a fish meal plant. 
With every catch that ship brought home a funny situation 
arose: the fresh fish, kept in ice, sold at a much higher price 
than the frozen fish. After two years he gave up the experi- 
ment as he felt that the greater expense in freezing over icing, 
and the consequent lower price of the frozen fish, created a 
very critical economic problem. 

MR. H. HEINSOHN (Germany): The German freezer trawler, 
the Heinrich Me ins, has a plate-freezer of 8 tons per day 
capacity. The owners confirm Sir Fred Parkes' remarks. 
They claimed only one small gain: the sea time, or the fishing 
time of the vessel was longer. 

The quality of the deep-frozen fillets is excellent, a fact 
that is proved by the preference of the crew for frozen fish over 
fresh fish. 

MR. . ARCOULIS (Greece): He felt that conclusions based on 
the Northern Wave and the Delaware experiments were not 
very reliable as these boats were not worked on a business 
basis. As co-owner of a few fishing vessels with freezing 
equipment on board, he felt to be in a position to make the 
following observations: 

Question of cost: a freezer trawler costs much more than 
an ordinary trawler but is not more expensive than a 
diesel-electric trawler 

Freezing plants decrease the capacity of the vessel for 
storing fish 

Handling of frozen fish increases the cost of unloading the 
catch 

The question of handling on shore and storage presents 
other problems. It all depends on what is to be done 
with the fish. Circulating hot air to defrost the fish has 
been suggested, but it appears to be waste of money 

Quality: the fish is reported to lose its sheen and not to be 
good for filleting 

The conception of the Delaware as a trawler with freezing 
equipment was obsolete. In the Northern Wave there was no 
necessity for using plate-freezers. He has been practising 
air-blast freezing for over three years and found it quite 
successful. 



MR. S. O'MBALLAiN (Ireland): He noted that there had been 
much talk about freezing fish at set in the round, unloading it 



in port, thawing the fish, filleting it, and re-freezing the fillets. 
He felt that the main difficulty lies in the thawing period. 
Freezing and storing on die ship can be done under optimum 
conditions. The suggestion put forward of thawing the fish 
by flushing it with water overnight is most unsuitable. He 
was of die opinion that thawed-out fish should never be re- 
frozen, as the result was not comparable to iced fish under a 
certain age. The quality reduction was small, but the effect 
was that the fish had a lesser appeal to the public. 

DR. INC. GINO GIANBM (Italy): Several Mediterranean fishing 
enterprises have recently begun to fish in the tropical waters 
of the Atlantic Ocean. The catch is frozen immediately after 
it has been washed and sorted, and the frozen fish is sold in 
various Mediterranean harbours. Satisfactory marketing ar- 
rangements have been established for the frozen fish and the 
good quality and low price are greatly appreciated by the 
consumers. 

These projects have been a great success, partially due to the 
unfavourable state of the traditional fishing activities and to 
the depletion of the fishing grounds in the Mediterranean Sea, 
but also due in a great measure to the new freezing methods. 
Freezing is nearly a perfect way to preserve and store such a 
highly perishable product as fish. These projects also show 
that freezing is the safest way to offer a cheap and high-quality 
product to large sectors of the population, ensuring at the 
same time good profits to the fishermen. 

Freezing plants on fishing vessels were not previously very 
common and there were no precedents of an industrial 
character to encourage the installation of such plants. Several 
circumstances have probably interfered with the introduction 
of freezing methods, such as the conservatism of fishermen, 
the prejudice against frozen fish by merchants and consumers, 
and perhaps also some mistrust of the technical installation, 
together with the general opinion that freezer trawlers had to 
be large vessels. By experience, freezing equipment requires 
a perfect knowledge of its operation, particularly so on small 
trawlers where the crew have not only a limited technical 
knowledge but also very inadequate repair and maintenance 
facilities. The equipment has to be simple, strong and safe, 
properly designed for working in tropical areas, and capable 
of being operated in a limited space. However, the freezing 
equipments so far installed have fulfilled these conditions, have 
proved to be easy to operate, and are now in common use* 

Perhaps the first freezing plant to be installed on a medium* 
sized fishing vessel was during 1951 at Genoa on the Greek 
Evridiki. The owners planned to fish along the Atlantic shores 
of Africa, freeze the fish as soon as it was caught, and market 
the frozen product in Piraeus. Lacking experience in this 
field, a number of initial difficulties had to be overcome, 
especially as regards the installation and the operation of die 
plant. But the project proved to be a success because of the 
trouble-free operation of the equipment and the fact that the 
product was welcomed by all kinds of consumers. 

This ship, still sailing the seas, has a length of 124 ft. 
(38 m.) and a displacement of 400 ton, it is powered by a 
450 h.p. engine, has a speed of 11 knots and is provided with 
an ammonia plant having a refrigerating capacity of 715,132 
BTU/hr. (180,000 kcaL/hr.), working with two compression 
stages and operating two freezers at a temperature of 40 to 
-49F (-40 to -45Q, abte to produce about 6 tons of 
frozen fish a d*y f and to refrigerate the 9,900 cu. ft. (280 cu.m.) 
ftshhokUatatemperatureof-4 to-13 F(-20to-25 Q. 
Hie holds have a capacity of only 264,000 to 286,000 Ib. 



[249] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 




/Hr. ,W7. flrir Gree* freezer trawler Evridiki operating in the South 
Atlantic and having vertical blast freezers 

(120 to 130 ton) of frozen fish and this has limited her profita- 
bility. The ship is shown in fig. 207 and 208. The Evridiki 
has worked excellently since 1952 without any particular 
interruption, making about five or six fishing trips every year, 
which, for such a ship, is really a remarkable achievement. 

This early experiment showed that a number of the objec- 
tions, which are still heard today, can be ignored. Some of 
these were a mistrust of ammonia as the refrigerating agent, 
the use of finned coils in the evaporators, high speed com- 
pressors and automatic control devices. The experience has 
given dear proof that a two-stage ammonia plant with proper 
characteristics can be installed on medium-sized fishing vessels 
and be operated with confidence by ordinary fishermen. 

The Atlantis High Sea Fishing Company of the Piraeus, 
owners of the Evridiki, are certainly of this opinion, because 
they equipped two more trawlers with the same system but on 
a bmer scale. The refrigeration plant, itself, is toss cramped 
became the *hips ate about 229 ft. (70 m.) long and 29.5 ft. 
<9 m.) wide. The plants have a refrigerating capacity of 
1,587,000 BTU/hr. (400,000 kcal./hr.), designed to freeze 



about 33,000 Ib. (IS ton) of fish a day and to keep a tempera- 
ture of - 13F (~~25Q in the fish holds of about 28,250 cu, ft. 
(about 800 cu. ITL). The vessels are powered by 1,200 h.p. 
diesel engines, and they are also provided with 500 kW 
generating sets and their longitudinal section is shown in 
fig. 209. 

In 1955 Messrs. Evangelistria of the Piraeus decided to 
have their 500 OT transport vessel Grassholm converted into 
a trawler by the same firm which converted the Evridiki. 
The trawler was renamed Evangelistria L The operating 
results were such that her owners decided almost immediately 
to do the same with two more second-hand ships. 

While the conversion of the Grassholm was a very unusual 
and difficult technical task as the ship was once a mine- 
sweeper, later converted to a merchant vessel, the installation 
of freezing plant in the other ships presented fewer difficulties. 
Nevertheless, Evangelistria 1 has been operating profitably for 
three years with a production of about 2,200,000 Ib. (1 ,000 ton) 
of fish a year. She has a length of 157 ft. (48 m.) and is 
powered by a 650 h.p. diesel engine, giving her a speed of 




Fig. 209. Longitudinal section o/ Evridiki II and 111 

11 knots. She is provided with a 1,190,000 BTU/hr. (300,000 
kcal./hr.) refrigerating plant, complete with four freezers 
capable of producing 26,500 Ib. (12 ton) of frozen fish a day. 
Her two holds have a volume of about 14,100 cu. ft. (400cu.m.) 
cooled to a temperature of -13F (-25Q and can carry 
about 510,000 Ib. (230 ton) of frozen fish. The freezing 






fig. 208. 



nt 0/Evridiki I refrigerating 
[250] 



FISH HOLDS DISCUSSION 



process is similar to the one on board the Evridiki, but it is 
somewhat simpler and provided with a number of special 
devtoes for quick defrosting. 

The two converted second-hand ships were renamed 
Evangelistria II and Evangelistria 111 (fig. 210), and apart 
from some slight differences in the volume of the fish holds 
and in their superstructures, they are fundamentally similar 
to one another. 

Their technical characteristics are: length 117 ft. (54 m.); 
beam 27.9 ft. (8.50 m.); draught 12.5 ft. (3.80 m.); speed 
13 knots; main engine 1,100 h.p.; 3 diesel generator 
sets with a total output of 350 kW. Refrigerating capacity 
1,389,000 BTU/hr. (350,000 kcal./hr.). 4 short vertical tunnel 
freezers (fig. 212). 

Quick-freezing capacity: 31,000 to 33,000 Ib. (14 to 15 ton) 
of fish a day. Volume of fish holds refrigerated to -13F 
(-25C): 21,200 cu. ft. (600 cu. m.). Capacity of fish holds: 
about 661,000 Ib. (300 ton) of frozen fish. Insulation of fish 
holds: 7.9 to 11.8 in. (20 to 30 cm.) porous cork slabs, with 
wood planking. Trawl winch power: 145 h.p., complete with 
Ward Leonard electric motor. Crew accommodation: 32 men. 

They were first of all completely stripped down to the bare 
hulls. Then complete reconstruction of the inside began: 
insulated holds, main engines, crew accommodation, installing 
all the new equipment and machines and so on. Where 
necessary, the hull structures were replaced, modified or 
supplemented. The conversion took about four months, of 
which one month was for dismantling and three for the 
rebuilding work. The decision to convert instead of building 
a completely new trawler might be questioned. Although it 
is true that each such case must be carefully examined, after 
studying the particular vessels under discussion, it was 
decided that both time and money would be saved by con- 
verting these particular ships. Actually, cost of conversion 
was a third less than it would have been to build a new ship 
similarly equipped. 

There was a great deal of discussion whether diesel-electric 
or diesel engines should be installed. Notwithstanding the 




Fig. 21 L Evangdistria in on trial 

advantages of diesel-electric power, it was decided to use the 
common diesel engine as the owners thought that this system 
was much more reliable with the crews they could recruit. 
This choice of power is debatable. In fact, these ships have 
three motor generating sets with a total output of about 
400 kW, a part of which is used for the Ward-Leonard system, 
while the other part has to work at a constant voltage. Con- 
sequently, both the circuits and the control-board are rather 
complex and require, anyway, qualified technicians. There 
are usually three electricians in these ships, one of them 
being specially required for attending the refrigerating 
equipment. 

The power required for the winch and the refrigerating 
installation is a factor that influences the choice and the sub- 
division of the electric generators' outputs. It is necessary for 
the winch to have its own generator. A second constant 
voltage set supplies the requirements of the refrigerating 
installation, while a third is a stand-by. This arrangement has 
proved practical and efficient. 

The refrigeration and freezing equipment require consider- 
able power which has to be generated in a very limited space; 
therefore it must all be of minimal overall sizes, for example, 
by using high speed compressors. The equipment occupies 






Fig. 210. General arrangement of Greek frteter trawlers Evangelfctria II and ITI 

[251] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 




Fig. 212. Short vertical blast freezers, being used with great success 

on fresh whole fish. They are kept in wire mesh boxes both when 

being frozen and in storage 

about 215 sq. ft. (20 sq. m.) for an installed power of 160 h.p., 
with a total weight of 66,000 to 77,000 Ib. (30 to 35 ton). 
The absorbed power for freezing alone at full load is about 
50 kW or 68 h.p. It is advisable, as a rule, that the refrigerating 
capacity does not exceed 50 per cent, of what is considered to 
be the daily average fishing capacity. Ammonia as the 



refrigerant has proved satisfactory in every way, and it i 
safer than freon. The main advantages of ammonia tie: 

m Distribution and control devices arc very ample and 
sturdy 

% Maintenance is easy even with unskilled labour 

Recharging does not need special care or precautions 

A high volumetric output is obtained with a low absorbed 
power 

The refrigeration plants in these ships have automatic 
control and are composed of a two-stage ammonia circuit 
for the freezing and of a single-stage one for the holds. Each 
of the three compressors is directly driven by a variable-speed 
electric motor. 

As far as possible all the connections should be welded and 
no cocks, valves,, etc. should be in the holds. All controls, 
automatic or manual, should be within easy reach. The use 
of switches or devices relying on mercury was avoided, 
because the ship's motion could interfere. All controls have 
been so designed and arranged as to reduce manual operation 
as much as possible and improve safety. Thus in the three 
years operation of the Evangelistria trawlers and the seven 
years operation of the Evridiki there have been no breakdowns 
or failures. 

Four blast freezers are used, having a short vertical freezing 
tunnel and with specially designed self-locking doors to avoid 
condensation. The freezers are of the standard liquid ammonia 
flooded type, properly recirculated by pumps. Special care 
has been given both to the feeding system and to the recircu- 
lating pump, one ammonia surge-drum being used for the 
four freezers. This arrangement allows an easy working, even 
when loading and unloading the freezers, as well as when 
defrosting. 

After washing and gutting, the fish is placed in small wire- 
mesh boxes for loading in the freezer. When frozen, the boxes 
go directly into the refrigerated holds. This layout has proved 
much more practical than the Evridiki's* where the frozen 
fish has to be carried back into the processing room before 
entering the holds. The layout may vary as, for instance, 
when the fish has to be glazed. In general however, it is 
advisable not to have the freezer doors opening towards warm 
rooms, as this is very uncomfortable for the crew. 

The freezers are loaded and unloaded by hand. In theory 
there are no difficulties in making them automatic, but on this 
type of vessel the conditions are not satisfactory for safe and 
proper working of such devices. 

Each freezer is fitted internally with a pair of axial-flow 
fans directly driven by an electric motor of the enclosed type. 
Each freezer has a pair of cooling coils, complete with finned 




Fig. 213. Profile 0fIt*U**fre***r trawler Gtnepcaca IV 
1252] 



FISH HOLDS DISCUSSION 



pipe evaporators, and well recessed to avoid damage. This 
gives alleviating surface in a small space. The necessary 
defrosting is done manually with hot gas, onoe or twice a day 
. in about 10 min., and when the freezer is empty. It deans the 
surfaces perfectly and removes about 4.5 to 6.3 Imp. gal. 
(20 to 30 L) of water each time. This water is discharged 
through a pipe into the bilge, which is kept dosed during 
freezing operations. 

Fish holds am refrigerated by means of 1| in. (42 mm.) 
plain piping, working on direct expansion and controlled by 
thermal expansion valves. It would not be difficult to attain 
lower temperatures but it would lead to a considerable loss of 
space on account of the thicker insulation. The frozen fish, 
however, is not kept in the refrigerated holds for a long time, 
so a temperature of - 13F (-25C) has proved to be satis- 
factory. The temperatures are controlled by means of tape 
recorders, besides the usual distance- and mercury-bulb 
thermometers. 

The holds are insulated with first quality porous cork slabs, 
8 in. (20 cm.) for the floors, and up to 10 to 12 in. (25 or 
30 cm.) for the ceiling. The insulating cork slabs are fitted 
on the ship's frames with offset joints. The inside covering is 
of wood, sometimes covered with galvanized steel or anodized 
aluminium sheets. This type of insulation is sound and strong, 
although it is somewhat bulky and expensive. For example, 
a fish hold of 14,000 to 28,200 cu. ft. (400 to 800 cu.m.) is 
reduced by about 18 per cent, in volume by the insulation. 
The useful volume of a fish hold is an important factor and an 
accurate study was made for all ships in order to get the best 
utilization of space, even at the cost of some sacrifice in 
the accommodation for the crew. The trips between the 
Mediterranean and the Atlantic represent a time, so that 
inadequate holds, although satisfactory in other respects, 
might not be in a favourable competitive position. 

Based on the experience gained, several other ships are now 
being converted, and entirely new vessels are projected. The 
new Evangelistria ships will have considerably different and 
much more complex characteristics and they will be classified 
as factory ships rather than freezer trawlers. Their re- 
frigerating capacity will be 2,000,000 BTU/hr. (500,000 kcal./ 
hr.), capable of processing about 44,100 Ib. (20 ton) of frozen 
fish a day. Their fish holds will have a volume of about 
46,000 cu. ft. (1,300 cu. m.) kept at a temperature of - 13F 
(~25Q, 

The results of this long experience of freezing at sea may be 
summarized as follows: 

Freezing at sea can be considered practical and perfectly 
safe 





Ftg.214. 



lV fawingkolds 



Fig. 2/5. Section showing refrigerating machinery and freezers of 
GenepescalV 



Fish must be frozen as soon as possible 

Blast freezers, if properly designed, are simple, strong 
and easy to handle. They give the greatest flexibility 
because whole fish both large and small can be frozen 
in trays or in various types of packing, as well as fillets. 

Difficulties with frost are totally removed by accurate 
design of freezers and simple defrosting devices 

Installations must have adequate air velocities and 
temperatures to ensure a perfect freezing. A refrigerant, 
such as ammonia or freon, can be used; the former has 
proved to be reliable, simple and safe 

The problems posed by the construction of a freezer 
trawler, or by a conversion, are not simple. The re- 
frigerating engineer and the shipbuilders should be con- 
sulted at an early stage 

Freezing at sea is definitely out of the experimental stage, 
and is a working tool at the disposal of fishing enterprises. 
It will certainly be considerably used in the near future, 
especially in areas where the traditional short distance fishing 
activities are on the decline. 

More Italian experience 

DR. ORAZIO Osn and CAPTAIN WALTER COSTA (Italy): 
Gcnepcsca IV was formerly used for salt cod production. In 
1957 she was converted to freeze and store frozen fish and 
to make fish meal. The main particulars of the ship, built at 
Le Havre in 1937, before conversion were: length 218.2 ft. 
(66.50 m.); beam 34 ft (10.36 m.); depth 19.7 ft. (6.00 m.); 
1,220 OT; 679 NT; two holds: total volume 40,153 cu. ft. 
(1,137 cu. m.); 6-cyl. main engine, 1,200 h.p.; two 180 h.p. 
auxiliary engines. 

The new refrigerating equipment of Gtntpesca IV, fig. 213 
to 215, is sufficient for fhe following white fishing in tropical 
waters: 

Freezing 20 tons daily by four freezers 

Preserving 400 tons frozen fish at a temperature of 
_ 4 o to _go F ( _20 to -22Q in the two holds 

The main features are shown in fig. 216 ami can be sum- 
marized as follows: 

% Direct ammonia expansion for freezers and holds 
% Multi-stage expansion with deep intermediate sub- 
cooling between the stages 



[253] 



FISHING BOATS OF THE WOULD: 2 CONSTRUCTION 




Fig. 216. The refrigeration circuits of Gcncpesca IV 



Forced circulation with electric ammonia pumps, for the 
evaporators in the holds and the freezers 

Four independent units with two-stage low-speed com- 
pressors; one being a spare 

Subdivision in three circuits, each at a different operating 
temperature 

Interconnection between compressors and between cir- 
cuits 

Automatic regulation of refrigerant, high degree of safety 
hi operation and easy control 

The refrigeration machine room is in the 'tween-deck. 
Each of the four units is driven by a DC motor and connected 
to a shell and tube condenser. Two units are for freezing; 
the third is normally used for cooling the holds; the fourth as 
a standby. 

Electric energy is provided by two diescl-elcctric units of 
100 kW each* placed in the engine room. One of these 
.generators is a standby. 

The refrigerating capacity of each compressor for the 
freezer is about 40 RT (150,000 keal./hr.) between 14 and 
77TF (-10 and + 25Q; the electric motor is 55 h.p. The 
refrigerating capacity of each compressor for the holds and 
for the spare is about 22 RT (85,000 kcal./hr.); the electric 
motor is 35 h.p. The compressors run at about 370 r.p.m.; 
tiiis low speed is very important for the heavy operating condi- 
tions in equatorial waters and it contributes to regular working 
and long life. 

The plant is divided into three suction circuits at different 
temperatures. The first and the second are for each of the 
freezers and are heading to the 40 RT compressors. The third 
circuit is for the holds and is connected with one of the 
22 RT compressors. 

The four large shell and tube condensers have roll-expanded 
pipes. The covere arc easily removable for periodical cleaning. 
The diameter of the pipes is larger than normal to facilitate 
cleaning and avoid excessive water speeds. All parts in contact 
with leawater are treated with a special anti-corrosive paint. 

The four freezers are placed under the machine room, 



directly communicating with the holds. Each freezer is 
divided into two compartments and each compartment has 
three shelves of galvanized coils. Air is forced uniformly over 
the fish and the evaporating coils in a horizontal direction. 
The fish is frozen in its wooden boxes. 

By having two compartments in each freezer temperature 
reduction is minimized. This division has also proved very 
useful to maintain identical conditions and even freezing; 
it avoids having to reverse the direction of the air blast 
periodically. Freezers are planned for -31F (-35C). It 
is not advisable to lower the temperatures too quickly so as to 
shorten the freezing time, because the quality of the fish 
depends on the right ratio between the speed and the tempera- 
ture of the circulating air. 

Defrosting is done by emptying the refrigerant into a large 
ammonia accumulator. Evaporators are defrosted by inject- 
ing hot compressed ammonia distributed by a branch pipe 
on the plant's discharge side. The fish holds are cooled by 
suitable smooth pipe evaporating grids applied on sides and 
ceiling. Holds* and freezers* doors are of "overlap" type. 

The ammonia is forced through the plant with four electric 
driven centrifugal pumps, of which one is a standby. The 




fig. 217. 



i IV 



{2MJ 



FISH HOLDS DISCUSSION 



pump* are fed from vertical ammonia surge drums placed 
over them. Electric driven pumpt are easy to regulate, being 
stable under load variations of the freezers and holds. 
. Among the several advantages of forced circulation is that 
the ammonia pipe can be installed according to the vessel's 
construction, there is no need to observe pipe slopes and level 
differences. 

The insulation of the separator and the low temperature 
ammonia piping is one of the synthetic resins. The insulation 
of the holds and freezers was made with several cork layers 
coated with bituminous emulsions on the surfaces. The 
average thickness of the cork linings is about 12 in. (300 mm.) 
in the holds and about 14 in. (350 mm.) for the freezers. 
The sides and ceilings of the holds are litosilo lined, white the 
internal surfaces of the freezers are covered with galvanized 
iron sheet applied on the wood boarding to which the cork is 
fastened. The volume of the frozen fish holds is about 
26,850 cu. ft. (760 cu. m.). 

Two rooms at the bow are used for fish meal production, 
the first for machinery and the second for 65 tons storage. 

The refrigerating plant has been carefully tested during 
many voyages to and from the fishing grounds near the 
Mauritania coast, which average 80 to 90 days and the 
experience was: 

Direct expansion ammonia system has proved to be both 
economical and technically sound in a large capacity plant on 
ships. Refrigerating units should be mounted on deck or 
tween-decks, ammonia circuits must be welded, shut-off 
devices must be outside the holds, and proper ventilation is 
advisable for the compressor room. These recommendations, 
of course, apply also to other refrigerants, so the use of am- 
monia therefore does not demand special conditions. The 
plant should be divided into circuits operating at different 
temperatures for each freezer and hold, and several inde- 
pendent refrigerating compressors should be installed. Two- 
stage compressors are suitable at the very low temperatures 
needed for freezing and they are as trouble-free as the normal 
single-stage machines. Forced circulation of ammonia, with 
electric pumps, is practical, efficient and reliable. 

Must study the market 

MR. MOOENS JUL (Denmark): In the discussion of the preser- 
vation of white fish at sea many calculations are made 
regarding the economics of freezing the whole catch at sea 
immediately upon capture versus storage of at least a large 
part of the catch in ice for landing it in this condition. It is 
generally agreed that the latter method is the more economic. 

It appeared to htm, however, that insufficient attention is 
paid to the fact that the landing of white fish which has been 
up to 10 or even more days on ice may very well be an 
obsolete process, and that consumers may soon demand a 
fresher product. Large population groups have for years been 
accustomed to the use of white fish which has been up to two 
weeks on ice. On the other hand, people accustomed to 
really fresh fish, i.e. 2 to 3 days on ice at the utmost, or fish 
frozen within a few hours after capture, will not eat such 
8 to 10 days old iced fish. The development in the U.S.A. has 
been that the whole distribution of fish is turning from fresh to 
frozen fish because it is in this way possible to supply the whole 
of the U.S.A. with fish of very good quality. This was not 
the case when iced fish was used. 

It is likely that the distribution of fish which has been 
iced for 10 days will be possible for several years to come 
but eventually wiH have to be discontinued. Since large parts 
of the white fish catches are fished far away from the place 



where the fish is landed there seems no alternative to freezing 
that part of the fish at sea. Therefore, fishing craft with 
capacity for freezing the complete catch will have to be 
developed for fishing giounds where shore bates cannot be 
established. 

Naval architects and fishing boat builders should study tile 
market investigations which food technologists have carried 
out. They are trying to predict what the consumers prefer. 
This is not an easy task but it is essential. Studies indicate 
that where frozen fish and iced fish of average quality compete, 
the frozen fish, prepared of really fresh fish, is preferred and 
gets a better price. It is true that freezing at sea is costly but 
it may become a necessity and the consumers may eventually 
be willing to pay the increased cost. 



Factors in fh 

COMMANDER M. B. F. RANKBN (UK.) : With regard to the use 
of refrigerated grids in wet fish rooms, it should be remembered 
that these were originally introduced in the days of poor 
insulation in steam vessels mainly to limit the amount of heat 
entering from the boiler room. The advent of the diesel 
engine had changed this and it was true that refrigeration 
was now somewhat of a luxury in Arctic waters except for 
preserving the ice on the outward voyage, but it was almost 
certainly essential for operation in warmer climates. DeSilva 
mentioned the need to have bulkhead and ship's side grids, 
presumably in warm waters and this was certainly desirable in 
conjunction with good insulation. Strakosch raised the 
question of frosted pipes and this problem had certainly been 
troublesome in some British distant water trawlers but means 
were available for defrosting the grids in turn to limit the frost 
build-up and leave the grids almost clean on entering harbour. 
Refrigerated spaces in which to prepare the fish before storing 
it were definitely desirable in warm climates and were an 
important feature of modern designs of factory trawlers 
designed for operation in warm waters. 

It was important to emphasize that the wet fish room cool- 
ing plant was only designed to deal with the heat influx from 
outside. It must not cool or freeze any of the fish in the hold 
below 32F (0Q and it must allow the ice to melt. 

Various remarks had been made about ice and the very 
large quantities which were required. Ice is by no means easy 
to obtain in many areas, particularly in warm climates, and it 
may be very expensive. It seemed probable, therefore, that 
chilled sea water offered a better solution for warm water 
fishing provided sufficient power could be provided to drive 
the refrigerating plant. 

Dreosti mentioned the particle shape of ice but this did not 
sound like a practical problem as it was dear that the cooling 
effect of a given weight of ice was always the same and the 
important thing was proper distribution through the fish. 
Washing of used ice between voyages did not seem practical 
by Dneosti's method and it would be better for the amount of 
ice remaining at the end of a voyage to be kept to a minimum. 

MacCailum mentioned belt driving of refrigerating com- 
pressors from the main engine of small fishing vessels. Alt 
attractive alternative would be to use a hydraulic motor with 
the pump driven by the main engine. This method was cur- 
rently used on a number of refrigerated vehicles and allowed 
the compressor to be sited in the most convenient place 
relative to the refrigerated space. 

MacCaihim's paper was obviously most valuable and would 
be used by many as their Bible. It was desirable, however, 
to raise one or two points. In table 40, MacCailum gave * 
figure of 0.08 BTU/hr,/aq. ft/F (0.391 teaL/hr./sq. m./<O 



{255] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



for the overall heat teakafe &ctor into A sted trawler, but 
this was lower than that recorded in many fully refrigerated 
ships and equalled the value obtained in trials in tix> Fair try 1L 
In British practice where the tank top was uninsulated and the 
bulkheads, deckhead and ship's sides had between 2 and 4 in. 
(51 to 102 mm.) of insulation, a figure of 0.15 BTU/hr./sq. ft./ 
F (0.734 kcal,/hr./sq. m./Q was commonly used for calcu- 
lating the heat leakage and this seemed more realistic. 
However, insulating the tank top as suggested by Strakosch 
would improve this figure and this was very desirable. The 
analysis of the optimum insulation thickness in relation to ice 
carded and fish hold capacity was most interesting, particu- 
larly in relation to warm water fisheries. 

The water-tightness of the insulation was of paramount 
importance both on the outside and on the inside and this 
was rightly empahasized by MacCallum. However, the 
Minikay system was not a satisfactory method of sealing the 
inside of the insulation in ships as it was almost impossible to 
ensure a vapour-tight internal lining between the hold and the 
Minikay ah* space due to the working of the ship. As a result 
it was common to find that the produce in the store had lost 
weight. The system was often ideal on shore but was not 
worth considering on board ship although it had been fitted 
extensively by some West European and Scandinavian shipping 
lines as well as in at least two frozen fish holds in trawlers. 

Mention should be made of the polyurethane light-weight 
rigid foams, which appeared to have a great future, particu- 
larly for tow temperature fish holds and for doors and hatch 
plugs. They showed promise of having a completely sealed 
structure and were cheaper to erect than other cellular 
materials in common use. 

MacCallum stated that aluminium foil was satisfactory so 
for as water absorption was concerned. This might be true of 
the material itself but it was not true of an insulated structure, 
as moisture could penetrate easily between the layers and 
freeze. 

For frozen fish holds, the principle must be to keep the 
heat leakage to a minimum and so limit the refrigeration load. 
This in turn limited the amount of desiccation of the frozen 
fish, a most important point when fatty fish were involved. 
In general the equivalent of 12 in. (30 cm.) of cork (8 in. 
or 20 cm. over beams and frames) was required in Northern 
waters and rather more might be needed in warm climates. 

The jacketed hold was the ideal but was not a practical 
proposition where space was at a premium and water-tight- 
ness of the inner lining could not be ensured. 

He hoped that Slavin would forgive him for saying that he 
had undertaken an unhappy and indeed an impossible task 
in trying to compare the relative merits of the Delaware and 
the Northern Wave. On the one hand was a ship and a fishery 
with which he was intimately connected, while on the other 
was a ship he had never seen and a completely different fishery * 
of which he obviously had no personal knowledge. Eddie 
dealt in detail with Slavin's paper. Only one or two points 
would be dealt with and a description given of the freezing 
equipment proposed for any new commercial vessel of this 
type which might be built for British owners. 

UstM prototype 
A vertical plate-fr 



(fig. 218) was developed for the 
Northern Wave from a prototype built by the Torry Research 
Station, Aberdeen* and was in every sense A robust, practical 
and reliable unit, which never gave any trouble throughout 
the experiment, in spite of its situation at the forward cod of a 
violently pitching mseL Thecydc time for loading, freezing 



and unloading the freezer* was 4J hn, and on this basis the 
freezing capacity of the whole plant was 646 lb./hr, (294 kg./ 
hr.) to - 20F (- 29C), not 500 lb./hr. (221 k*/hr.) as stated 
in Siavin's paper. In the Northern Wave, blocks 36 x 18 x 
4|in. (915x457 xU4 mm.) thk and weighing 64 Ib. (29 kg.) 
were produced. For the future a block size of 42x21 x4 in. 
(1,070x535x102 mm.) thick, weighing 84 Ib. (39.2 kg,) 
was suggested. Hie installation proposed for a standard 
British diesel or dicsel-electric distant-water trawler, 185 x 
32$ ft. (57 x 9.9 m.) would have 13 three-station units and with 
the reduction in block thickness to 4 in. (102 mm.) as well as 
improved refrigerant distribution and control, a freezing time 
as low as 3 hr. had been achieved, though in practice, 
3 j hr. would be allowed for a complete cycle. On this basts 
such a plant would have a freezing capacity of 875 lb./hr. 
(397 kg./hr.) to ~20F (-29Q; if the trawler's beam wens 
increased to 34 ft. (10.4 m.), a further three stations could be 
accommodated, which would raise the freezing capacity to 
945 lb./hr. (430 kg./hr.). Handling of the fish between the 
buffer storage pounds and the freezers is much reduced with 
this athwartships layout. 




Fig. 218. 



[256] 



FISH HOLDS DISCUSSION 



The Delaware** freezing plant could not be compared 
directly with that of the Northern Wave as it was freezing 
individual nth from about 1 to 4 in. (25 to 102 mm.) thick. 
Its capacity on thick ftsh only was presumably much less than 
that of the Northern Wave plant, a figure below 400 Ib./hr. 
(182 kg./hr.) being likely, Also the temperature of 0F 
(-18O was much above that found necessary in British 
practice, where -20F (~29C) was gradually becoming 
standard; this temperature was essential for the long storage 
of such fish as herring. He would not comment on the relative 
merits of brine-immersion and plate-freezers, but the former 
had not found favour hi the U.K. for many years past, 
although it was first used there before 1890 (British Patent 
No. 6117, dated 9 April, 1889). 



installation could only be really satisfactory in a ship specifically 
designed for the purpose. Conversions were always expensive 
and almost never ideal. 

It had often been said that most of the damage done to 
fish occured during unloading and subsequent handling on 
shore, and Slavin gave a graphic description of the unhygienk 
and primitive methods used today. It was to be hoped that 
far more thought would be given to this aspect both for fresh 
and for frozen fish. He looked forward to the day when 
human hands would not come into contact with the fish at 
any time after it entered the fish hold up to the time it was 
prepared for cooling. This was already technically possible 
for frozen fish though it was not yet current practice. How- 
ever, wet fish presented a bigger problem, and many changes 




Fig. 219. Proposed refrigerating circuit using single-stage Refrigerant 12 or 22 



To achieve the low temperature of -20F (-29Q was a 
considerable technical problem, as simplicity, reliability and 
ease of operation were essential in such small ships. Theo- 
retically a two-stage refrigeration plant would be the right 
solution, but it was found that for this application a single- 
stage Refrigerant 12 (Arcton 6/Freon 12) or Refrigerant 22 
(Alston 4/Froon 22) plant, evaporating at -40F (-40C) 
was preferable and need not occupy excessive space. The pro- 
posed basic circuit was shown in fig* 219. In a diesel-ckctric 
trawler with a constant-current system, the possibility had 
been considered of including the freezing compressor as well 
as the trawl winch motor in the constant-current loop. A 
fully automatic plant with a single compressor also appeared 
practical, reliance being placed on capacity reduction and 
speed control to balance the refrigeration load under all 
conditions. 

Some further information on the above scheme was given 
in the paper by Eddie. He agreed with Slavin that such an 



in the organization and distributing fish would have to be 
made. 

Arcoulis saw no point in using plate-freezers but in the 
conditions of the Arctic fisheries with very high catching rates, 
everything possible had to be done to reduce the freezing time 
while preserving the quality. The vertical plate-freezer could 
freeze 4 in. (102 mm.) thick blocks in as little as 3* hours 
compared with at least five hours in a freezing tunnel. 

It was now common to thaw, fillet, and refreeze such large 
fish as cod and haddock and little was lost in the process pro- 
vided that the initial freezing was done within the time limit 
and to the right low temperature. 

Gianesi's very valuable contribution touched on some of the 
great problems involved in freezing fish in warm waters. 
Firstly there was the rapid onset of rigor mortis which 
necessitated either very rapid chilling or immediate freezing. 
In the la tier case great difficulties were encountered with rapid 
frost formation on the tunnel air coolers and this was 



[257] 



PISHING BOATS OF THE WOULD: 2 CONSTRUCTION 



.This showed the 
desirability of pre-cooHng the fish before freezing, of limiting 
infiltration to die runnels, and of air conditioning die working 
spaces to as low a temperature and humidity as possible, as 
was proposed for a number of projected designs of factory 
trawlers. 

While appreciating the reasons for the choice of ammonia 
as the refrigerant he could not agree with Oianesi that this 
dangerous refrigerant was desirable in a small ship. A 
Refrigerant 12 or 22 plant either single-stage or two-stage was 
infinitely preferable and could be just as reliable and fool- 
proof with careful design. He doubted whether ammonia 
would be tolerated by any British owner. In ship's rotary 
boosters followed by high speed V-dcsigns of reciprocating 
compressor were desirable to save space. 

Sir Fred Parkes and Heinsohn had said that frozen fish 
could not command such high prices as could fresh fish. This 
had been true in Western Europe and the U.K. principally 
because of unsatisfactory freezing methods and bad handling 
of the fish resulting in poor quality. Coupled with this was the 
fact that no Western European country had a satisfactory 
organization for marketing frozen fish. When these funda- 
mental points had been dealt with there was no reason to 
doubt that frozen fish would be able to hold its own against 
fresh fish, and in many cases surpass it, as had already 
occurred in UJS.S.R., U.S.A. and Greece. Jul had high- 
lighted the crux of the matter when he said that the customer 
may eventually be willing to pay the increased cost. 

State of ice important 

DR. O. M. DRBOSTI (South Africa): In commenting upon the 
use of ice, Ranken has apparently missed both points entirely. 
The particle shape of die ice naturally cannot affect the 
amount of cooling that can be obtained from a given weight 
of ice. That depends on the weight of ice alone. The rate at 
which fish can be cooled by that weight of ice, however, 
depends very largely on the particle shape and size of the ice. 
It is therefore the cooling rate, and not the total cooling effect, 
that is affected by particle size and shape. 

In connection with the washing of used ice he could only 
say that in South Africa used ice is washed regularly and 
reused, not in the trawlers but in the railage offish up country. 
Ice costs about 1 4s. per short ton, whilst water costs only 
5d. per short ton. It is definitely an economical and indeed a 
very simple procedure. In South Africa it is very practical. 



REPLIES OF AUTHORS 

DR. G. A. REAY and DR. J. M. SHEWAN (U.K.): They did 
not wish at this stage to contribute anything further to the 
discussions other than to make some general remarks. They 
thought that Dreosti had made several important points in his 
contribution, particularly with regard to the different rates of 
cooling offish in different positions in the hold; under layers 
of fee of different thicknesses; and when "flake" and crushed 
block ice are used. His enumeration of the striking ad vantages 
claimed for the use of the fish flume on board ship was also 
read with much interest. 

MacCattum commented that fish hi some circumstances, 
and in particular in contact with wood, although chilled with 
ice can spoil more rapidly than shown in table 45, they would 
ttoe to have an assurance from MacCaHum that he has in 
fcct measured the tcnqxratures of the fish under the cinmm- 
staaoes he specified. In their experience it cannot be assumed 



that fish in direct contact with wood, even although otherwise 
surrounded with ice, are at 32F (0Q the Adi i& usually a 
few degrees higher- and the more rapid spoilage claimed by 
MacCallum may in fact be due in some measure to a tempera- 
ture difference. 

Answering Proskie: they had not had as yet sufficient 
experience with chilled seawater to be able to give a balanced 
opinion as to the merits of this method of chilling as against 
icing. It is considered, however, that where the age of the 
first caught fish at landing never exceeds six to eight days, 
chilling would give as good an article as sea-frozen fish at 
landing. Moreover, it is doubtful whether it would be feasible 
or practical economics to instal freezing plant on board such 
small vessels. 

They had no .comments to make on Ranken's contributions. 

They had noted Slavin's remarks about the effectiveness of 
washing fish in 60 p.p.m. free chlorine prior to stowage in the 
hold, and thought it very important that the scientific data 
on which this claim is based should be made available for all 
to see. Slavin's further point about the ratio of 1 : 1 for fish 
and ice being too high might well apply to the vessels whose 
round trips are not of such long duration as those of the 
British distant water fleet and to which the values specifically 
apply. 

The several points made by Strakosch as applying particu- 
ilarly to conditions of high ambient temperatures are also very 
illuminating and would repay careful consideration by all 
interested parties. They serve to show, if nothing else, how 
difficult it is to generalize on matters affecting stowage of fish 
in a ship's hold, when the conditions under which the fishing 
is conducted can differ so widely. 

MR. W. A. MACALLUM (Canada): The naval architect will 
serve the fishing industry well if he applies available knowledge 
of fish preservation in the design and layout of fish handling 
and fish holding facilities aboard ship. He can bridge the gap 
between technology and practical application best by speci- 
fying necessary materials, procedures and arrangements 
when the vessel is in the planning stage. Mr. MacCallum's 
paper had been prepared to assist him in this important task. 

The method described for determining insulation require- 
ments of a fishing craft would appear to be practical, having 
in mind the need to preserve the catch and to minimize the 
labour of the hold worker and loss of hold space. Mr. 
MacCaHum wished to stress the need to make a wise choice 
of water-vapour proof membranes and insulations and to 
install them correctly. He did not feel that vibrations in the 
fish hold can be considered extreme and that they would 
contribute to the breakdown of polystyrene. The latter is 
reported to have been used with good satisfaction and without 
ill effects in insulated trucks where vibration intensity is 
probably higher than that experienced aboard the vessel. 

Ranken's comments are appreciated. His report to the 
effect that a U-value of 0.15 BTU/hr./sq. ft./F (0.734 kcal./ 
hr./sq. rti.ro is commonly used in U.K. for calculating heat 
leakage is significant One might well question but not 
necessarily condemn a practice which provides about half the 
effective insulation considered to be necessary for 32F (0Q 
storages on land. 

It may easily be shown that if a wall in a steel vessel were 
insulated between the flange of the frame and the inner lining 
of the fish room to a depth of 1 in. (25 mm.) and the spaces 
between frames were insulated to give an over-all U-value 
of 0.13 BTU/hr./sq. ft./F, the depth of crushed ice actually 
required under the otherwise unaltered conditions set out in 



[258] 



FISH HOLDS DISCUSSION 



Ubte 50 would be 2.3 in. (58 mm.). A saving of 3.4 in. 
(86 mm.) of crushed ice or 5.1 short tons (2,000 Ib.) per 1,000 
sq. ft. (5.0 ton per 100 sq. m.) of surface area of insulated wall 
would be possible over the case where the wall was not 
insulated. 

A U-valuc of 0.15 BTU/hr./sq. ft./F corresponds to an 
effective depth of corkboard of about 1} in. (37 mm.) only, 
where the insulation is incorporated into a fish hold wall (steel 
vessel). It is apparent that if minimal depths of insulation 
such as 2 to 4 in. (51 to 102 mm.) are used the greater portion 
of the insulation should be placed between the flange of the 
frames or stiffeners and the inner lining of the fish hold, 
otherwise a U-value of 0.15 BTU/hr./sq. ft./F will not be 
realized. It would be better still to insulate as heavily as 
economically feasible between as well as over frames. This 
should be more feasible now than ever before as a result of 
the development of suitable light-weight insulation. 

Theoretically, the jacketed fresh fish hold need not be a 
space waster. It could save space. Practice could match 
theory if the naval architect were to provide a fish room 
uniformly full from fore to aft. The Gregson system and the 
polyurethanc foams which can be incorporated into jacketed 
fish rooms appear to be quite adequate as far as providing 
water-tightness. In Mr. MacCaHum's opinion multiple unit 
pens could be incorporated also into a jacketed design which 
would have many pleasing and practical features. There seems 
little reason to doubt the success of the jacketed room from 
the engineering standpoint. Experience to date is not that 
alternatives to conventional construction are not satisfactory 
but that owners are loath and naturally so to increase 
capital expenditure when toe can be used successfully in place 
of a mechanically refrigerated jacket. In this connection it 
may be noted that builders have been under little or no 
pressure to develop cost saving techniques in jacketed hold 
construction. At any rate, radically changed techniques of 
hold construction in metal are apt to be fairly costly where 
vessels of a particular design are ordered in limited numbers. 

As suggested in his paper it may become common practice 
to specify metal for stanchions, divisions and portable boards 
and strong, durable, corrosion-resistant, non-metallic, water- 
tight materials for ceilings and walls of the fish room. Latex- 
sand-cement compositions and glass fibre reinforced plastics 
are two possibilities for the latter application. Latex-sand- 
cement should be placed over a rigid sub surface. Reinforced 
plastics may be used in the same way or in a self-supporting 
structure. Too few applications of either material have yet 
been made however to give a good cost comparison with 
metals, e.g. aluminium alloys, for the construction of water- 
tight jackets. 

Mr. MacCallum concurred with Reay's and Shewan's 
comments in their paper as to the role of deck grid refrigera- 
tion. It is his personal opinion that, in many instances, a 
very good case can be made for the use of a jacketed wet fish 
room. 

Slavin, Eddie (1958 b) and he was in agreement as regards 
the arrangement and design of stanchions to permit inter- 
changeability of pen boards. However, he did not feel that 
one should assert categorically that a fish room is best if it 
can be "built" and "torn-down" by the fishermen before, 
during and after each trip. "Wings" or portions of wings 
(transverse partitions) in aluminium alloys should be of 
movable boards when it is more convenient to ice and dis- 
charge the catch with such an arrangement that when parti- 
tions an wholly fixed and when this advantage is balanced 
against (1) the increased cost of handling and cleaning the 



boards, (2) shorter service life of the movable board as com- 
pared to the fixed sheet, (3) the more pleating appearance of 
the fixed sheet throughout its service life. On the larger 
trawler there can be a distinct advantage in having the inboard 
section of the wing of each pen "built" of movable aluminium 
alloy boards while on medium and smaller trawlers thane may 
be a distinct advantage in having fixed or permanent wings of 
aluminium alloy sheet; on trawlers of all sizes movable boards 
for "back halves" of wings (these being the sections between 
the outermost longitudinal row of stanchions and the ceiling) 
must be of various lengths and in the metal fish room are 
generally avoided, being replaced by fixed sheets. Everything 
else being equal, as many movable boards as can be handled 
conveniently and economically should be used in the wooden 
"wet" fish room since those responsible for maintenance may 
wash, dry and refinish these elements and operate a system 
which makes reconditioned boards available for installation 
at all times. 

Mr. MacCallum was pleased to have the results of Prunchie's 
laboratory tests of catalyzed finishes. It would be expected 
that their superiority over the others tested would be apparent, 
but in reduced measure, in fish hold applications. His 
experience with catalyzed finishes in the fish room was that 
they keep the wood covered for longer periods between refits 
than do conventional paints if they are applied under condi- 
tions favourable to their setting. However, they are not 
considered permanent nor do they prevent the underlying 
wood from gaining moisture. To make laboratory tests more 
useful to the buyer of the product, modifications of presently 
used accelerated tests would have to be made and results 
should be expressed in such terms as guaranteed fish room 
surface covering characteristics for a given period for various 
grades and species of wood, with moisture content of the 
wood, and temperature and humidity conditions at time of 
applying and curing the paint being specified. 

Slavin has again pointed out the perennial difficulty the 
inability to keep wet wood covered with paint. The paint 
chemist has not solved this problem. Possible alternatives 
were: 

Use wood : (a) in movable sections or boards which may be 
removed and dried thoroughly, albeit at high cost; (b) in 
fixed partitions, sides of fish hold, etc. only when it can be 
covered with screens, metal boards and painted wooden 
boards (all of which would be movable). In this case the 
lack of paint on the hidden surface has no effect on fish 
preservation. 

Use materials other than wood which do not require 
painting, e.g. aluminium alloys, fibre glass, reinforced plastic. 

Regarding Slavin's question on cleaning screens, Mr. 
MacCallum had not received reports of difficulties. It is quite 
probable that the frequency of removal of screens for cleaning 
need not be too great and most certainly will not be as great 
as that for movable boards. This should be the subject of a 
later report. 

Strakosch has referred to the use of zinc sheathing (i to 
1 mm. thickness) in fish^holds. One would expect the material, 
if suitably joined, to be satisfactory for some applications, 
particularly where fish are handled in small boxes. The gauge 
mentioned would be far too light for "wet fish" rooms where 
fish and ice and ice alone are stored in bulk. 

In the case of materials such as aluminium alloys, glass 
fibre reinforced plastics and plastic paints which are all new 
in the sense that shipbuilders are not too familiar with their 
use, the naval architect should know practicany as much about 
the material and its use as the manufacturer, so that through 



[259] 



FISHING BOATS OF THE WO&LD; 2 CONSTRUCTION 



design and installation techniques full advantage can be taken 
of the material. In thii way failure* which In truth might be the 
fault of the architect or the shipyard and not of the material 
todf, may be avoided. 

Fish handling and storage space and timber ventilation in 
small boats despite the worldwide importance of the latter 
have been neglected heretofore by the naval architect and 
the technologist. Mr. MacCallum had analyzed certain types 
of smalt boats, both decked and undecked, in these respects. 
It is hoped that this may serve as a basis of discussion for the 
naval architect ami the prospective owner of a new vessel. 

He concurred in the opinions expressed throughout the 
the proceedings concerning the desirability of reducing the 
amount of strenuous work and of providing less onerous condi- 
tions aboard the vessel Progress towards this goal could be 
made by giving the fishermen: 

Uniform and fully shaped fish-rooms from fore to aft, 
uniform boxes or uniform fish pens with uniform and 
interchangeable boards 

A practical method for handling larger catches in boxes 

A dean or protected (as with screens) fish room and fish 
containers made of materials which can be kept clean 

Insulation and refrigeration facilities to enable fish room 
air and surface temperatures to be kept at the desired 
level 

Suitable ice and means of handling it more easily 

MR. J. W. SLAVIN (U.S.A.): There is no question that the 
fishing problems for each part of the world differ considerably. 
Freezing fish at sea, as Arcoults pointed out, may solve many 
of Greece's fishing problems and provide that country with a 
plentiful supply of high quality raw material Yet, in other 
parts of the world, icing may be just as satisfactory. Therefore, 
only for evaluating, for each particular fishery, the factors of 
handling aboard the vessel, storage on the vessel, unloading 
and handling ashore, quality of the product and die associated 
costs can one determine whether freezing or icing is the most 
satisfactory. 

Several of the contributors mentioned that the Delaware 
and Northern Wave are experimental vessels and thus as 
such should not be used as a basis for determining the success 
of freezing at sea. This is not completely true for only by 
comparing techniques used on these experimental freezer 
vessels with those used on conventional king trawlers can 
remedies for existing problems be offered by naval architects, 
engineers, technologists and vessel owners and operators. 

Eddie in his contribution made the interesting observation 
that the fish frozen on the Northern Wave were soft because 
of biological factors due to catch areas, not because of the 
freezing process. This is a good point and shows that in 
freezing fish at sea much thought must be given to the 
differences in fish quality due to biological factors. Mf. 
Slavin mentioned that during a recent trip to England, he had 
a chance to view plate-frozen fish that were caught in a 
different area than those in the Northern Wave project; these 
fish were of very good texture. 

Eddie's statement that high grade products cannot be made 
by brine immersion freezing and cold storage at 0F (- 18O 
is without foundation. Fish brine-frozen immediately after 
catching and thra stored at 0F are of excellent quality. Also, 
storage at -20F (~-29*Q may only be necessary if the fish 
are iced for several days prior to freezing, as they were on the 
Northern Wave. In the U.S.A,, temperature* of -20F 
<-29C) are not practical for storing fish if they ate to be 
*-ng with other frozen foods. 



It was good to leant from Eddie that fish can be satis- 
factorily plate-frozen prior to rigor mortis and that it is not 
always necessary to wait until they pass through this stage of 
rigor mortis until the start of freezing. In U.S.A. it was found 
that freezing immediately when caught is essential in order to 
obtain a high quality product. 

It is true that the Delaware fish were produced to compete 
with fish that are normally marketed in the form of frozen 
fillets, whereas Northern Wave fish were produced to compete 
with wet or smoked fish. However, it was observed that fillets 
from thawed brine-frozen fish compared quite favourably to 
freshly landed fish. Also, Eddie implied that after a given 
number of days, the quality of fish on U.K. vessels seems to 
be higher than on vessels operating along the Western 
Seaboard of the Atlantic and that this influences the standard 
for comparison of sea-frozen fish. In evaluating this standard 
of comparison, Mr. Slavin pointed out that the length of time 
the fish are stored on the vessel is of prime importance and 
that, because of the long distance that British fishing vessels 
have to travel to and from the fishing grounds, fish landed in 
the U.K. are generally of much lower quality than those landed 
along the Western Seaboard of the Atlantic; he therefore 
could not agree with Eddie that the overall standard of com- 
parison for evaluating fish frozen at sea for the Northern Wave 
project was higher than for the Delaware project. The studies 
now underway in the U.K. on dielectric thawing of frozen 
fish are very interesting. This work should be closely appraised 
for possible application in other freezing processes. 

In regard to Ranken's discussion, it is difficult to determine 
what is meant by the capacity of thick fish. It is the overall 
rate of freezing (the number of pounds of fish that can be 
handled each hour) that is important, not the thickness of the 
fish or layers of fish. This is only important because it con- 
tributes to the rate of freezing. The rate of freezing should be 
equal to the mean catch rate in order to provide rapid handling 
of the fish and to minimize loss of quality. In this regard, the 
increase in freezing capacity recommended for future British 
freezer trawlers of over 875 Ib./hr. (397 kg./hr.) is a step in the 
right direction. Mr. Slavin now recommends that freezer 
trawlers for the New England fishery have a freezing capacity 
of at least 3,000 Ib. (1 ,360 kg.) of fish per hour. 

In regard to Mitsui's questions, on the Delaware, the baskets 
of fish were moved through the cold brine and the appearance 
of these fish was quite satisfactory. The fillets prepared from 
the brine-frozen fish had lost the bright sheen of regular iced 
fish; this, however, was not considered to be objectionable. 
Also, buffer storage refers to the hold where the fish on the 
Northern Wave were iced and stored for one to three days after 
being caught and prior to freezing. Details of the plate- 
freezing unit can probably be obtained from the Torry 
Research Station, Aberdeen, Scotland, U.K. 

In response to O'Meallain's question on water-thawing, 
this method has proven to be quite satisfactory for both 
haddock and cod; the thawed product being of very firm 
texture. These results may be influenced by the fact that the 
brine-frozen fish became quite firm due to the freezing process 
and, therefore, did not soften as much during water-thawing 
as did fish that were frozen by other more conventional 
means. 

It was most interesting to learn from Arcoulis and Gianesi 
of trtefiwzing of fish at sea on Greek ftshing trawlers. More 
information would be desirabte on the species of fish now 
being fron on these vesaete and on the methods for handling 
these fish on the vessel, and for thawing and storing them 
ashore. 



[MOJ 



PROPULSION ENGINES FOR FISHING BOATS 

by 
IVAR B. STOKKE 

The designs of two-stroke and four-stroke diesel engines are compared, giving the advantages and disadvantages and 

the two-stroke fufl-dieseJ engine may give 60 to 70 per cent, more power than a normally aspirated four-stroke engine of the same 

volume and r.p.m. Scavenging is simpler in a four-stroke diesel, especially by supercharging. Supercharging of the four-stroke diesel is 
discussed, and it is stated that 60 to 100 per cent, more power can be obtained thereby. The high pressure supercharged four-rtroke engine if a 
good competitor to the fully scavenged two-stroke engine. If, however, the two-stroke is supercharged, it will give a mean effective pressure 
of 85.5 to 99.5 Ib./sq. in. (6 to 7 kg./sq.cm.) which is equivalent to 171 to 199 Ib./sq. in. (12 to 14kg./sq.cm.)forahi^i$upei^iarfedfour^troke 
diesel engine, 

Recent developments in this field are dealt with, and a comparison of the space requirements for the various propulsion arrange* 
ments for trawlers is discussed. The reverse reduction gear with two reduction ratios ahead is discussed, as well as the controllable-pitch 
propeller with direct drive to the propeller. It is mentioned that a controllable-pitch propeller is better suited for this propelling system than 
a fixed-blade propeller when considering the various propulsion requirements for trawling and sailing. 

If the conventional electric drive of the trawl winch is replaced by hydraulic drive, the space requirements will decrease. The hydraulic 
winch drive is more simple, robust and elastic and is therefore better suited for hard working conditions, especially those met in colder regions 
where trawling is often taking place. 

A short outlook into the future development with diesel-electric propulsion, free piston gasifiers and gas turbines for big trawlers is 
given. It is warned against using too fast-running engines (1,500 to 2,200 r.p.m.) for fishing craft propulsion, because these light-built engines 
cannot stand the hard night and day working conditions without being worn down quickly. 



MOTEURS DE PROPULSION POUR LES NAV1RES DE PECHE 

L'auteur compare les conceptions des moteurs diesel a 2 temps et a 4 temps en donnant leurs avantages et inconvenients. II indique 
que le moteur diesel a 2 temps peut fournir une puissance plus elevee de 60 a 70% qu'on moteur a 4 temps & alimentation normale et ayant 
la meine cylindree et le meme nombre de t.p.m. Le balayage est plus simple dans un diesel & 4 temps, speciatement par suralimentation. 
La suralimentation du diesel a 4 temps est examinee, et 1'auteur declare que Ton peut ainsi obtenir une puissance plus elevee de 60 & 100%. 
Le moteur a 4 temps suralimente' sous pression 61evee est un bon concurrent pour le moteur a 2 temps a balayage total. Cependant, si k 
2-temps est suralimente' il donne une pression efficace moyenne de 85,5 & 99,5 Ib/pouce carre* (6 a 7 kg./cm 1 ) qui est equivatente aux 171 & 
199 Ib/pouce carre (12 a 14 kg./cm*) pour un moteur diesel 4 temps a suralimentation poussee. 

II est trait* des recents d6veioppements dans cc domaine et 1'auteur examine la comparaison des exigences d'espace pour les divers 
dispositifs de propulsion pour les chalutiers. Le reductcur a rcnversement de marche avec deux rapports de reduction en avant est compare* 
a rhelice a pas variable avec entramement direct de I'helice. II est mentionne* qu*une hetice & pas variable convient mieux pour ce systeme 
de propulsion qu'une helice a ailes fixes quand on considerc les diverses exigences de propulsion pour le chalutage et la route libre. 

Si rentralnement electiique courant du treuil de chalut est rempTace' par 1 entratnement hydraulique, cela dimtnue les exigences 
d'espace. L'entralnement hydraulique du treuil est plus simple, plus robustc et plus elastique, et il convient done mieux pour les conditions 
de travail dures, specialement celles recontrees dans les regions froides ou on chalute souvcnt. 

L'auteur donne un court apergu du developpement futur de la propulsion diesel Electrique, par turbines A gaz et gene>ateurs & pistons 
libres pour lea gros chalutiers. II met en garde contre 1'emploi de moteurs trop rapides (1 ,500 a 2,200 t.p.m.) pour la propulsion des fratftnux 
de peche, parce que ces moteurs de construction legere ne peuvent pas supporter les dures conditions de travail nuit et jour sans dtre 
rapidemeni uses. 

MAQU1NAR1A PROPULSORA PARA BARCOS DE PESCA 

Se comparan los proyectofi de motores Diesel de 2 y 4 tiempos; se citan sus ventajas e inconvenientes y se menciona que un motor 
Diesel de 2 tiempos puede rendir de 60 a 70% mis potencia que un motor de 4 tiempos aspirado normalmente, de iguates cilindrada y r.p.m. 
La evacuad6n es mas sencilla en el motor de 4 tiempos, particularmente por sobrealimentacion. Se examina la sobrealimentacion del Diesel 
de 4 tiempos y que se afirma que con ella se puede obtener de 60 a 100% mas fuerza raotriz. El motor de 4 tiempos, sobrealimenudo, de 
gran presion, es un buen rival del motor de 2 tiempos. Pero si se sobreaumenta el motor de 2 tiempos, daii una potendafectrva media lie 
35,5 a 99,5 Ib./pulg 1 (6 a 7 kg./cm 1 ), que equivale a entre 171 y 199 Ib./pulg* (12 y 14 kg./cm*) para un motor Diesel de 4 tiempos muy 
sobrieanmefitado* 



Se examma 

de pato variabte es m^* admaiada para la transmisi6n directa que la de palas fijas. 

Si en higar de la transmition electrica normal de la maquinilla de pesca se emplea la hidraulica, se reducen las necesidades de espacto. 
La transmision hidrtulica de la maquinilla de arrastre es mas sencilla, robusta y elastica y, por tanto, mis conveniente para las condkaones 
de trabajo duxas, espedalmente las que se encuentran en las reaones frias en las que se pesca mucho al arrastre. 

Se menciona brevemente el futuro de la propulsion Diesel electrica, gasificadores de piston libra y turbinas de gas para arrastreros 
grandet. Se hace una advtrtencia contra el empleo de motores muy revolucionados (1.500 a 2.000 r.p.m.) para la propulsion depcsquerot, 
porque estos motores liieroa.se gastan rapidamente cuando se someten a las duras condiaones de trabajo diarias. 

a [261] 



FISHING BOATS OF THE WORLD: 2 CONSTRUCTION 



CURING recent years there have been rapid 
in propulsion engines for fishing 

r vessels, not only in design but also in the use of 
better materials, fuel and lubricating oils. 

There is still competition between the four-stroke and 
the two-stroke systems. The two-stroke is simpler in 
design, especially with Curtis or loop scavenging. But 
the design becomes more complicated when the scaveng- 
ing and exhaust ducts are placed both in the cylinder 
liner and in the cylinder block. This design also requires 
many seals, especially between the cooling space and the 
exhaust and scavenging ducts, and that complicates the 




fig. 220. Wichmann engine, with built-in hydraulic reverse gear 



maintenance. Some of these difficulties are not great in 
very big two-stroke diesels, where the ducts can be 
finished after the cylinder liner has been placed in the 
cylinder block. It is important to design cylinder liners 
with the least possible concentration of material around 
the scavenging and exhaust ducts (Stokkc, 1957). 



COMPARISON OF TWO- AND FOUR-STROKE 
DIESELS 

The two-stroke system with uniflow scavenging has 
scavenging ducts in the lower part of the liners, while the 
exhaust gas escapes through valves (or a valve) in the 
cylinder cover. This results in a more constant tempera- 
ture in the cylinder liner and improved lubrication of the 
cylinder wall. The wear on the cylinder liners is also 
decreased because the exhaust escapes the shortest way. 
The piston top is also better cooled by cold air. Uniflow 
scavenging requires a longitudinal camshaft to operate 
the exhaust valves, but the injection pumps, etc., can also 
be driven from this camshaft so that one pump can be 
placed near each cylinder. The fuel pipes to the nozzles 
wiH be short, facilitating efficient working conditions 
for the injection equipment. The tightening arrangements 
between the cylinder liner and the cylinder block are 
simpler. There is a similar simplification and better shape 
of the scavenging and exhaust ducts when the cylinder 
Bner itsdf has a cooling water space (Wichmann). The 
same is true for the ducts of the two-stroke diesel with 
separate cylinders, but with a smaller cooling space in 
each cylinder (Alpha). This, however, makes the distance 
between the cylinders somewhat greater* Such a design 
is normally only used for cylinders with a bore diameter 



up to about 10$ to 11 J in, (270 to 290 mm.) because in 
larger engines a cylinder liner with cooling space could be 
too expensive to maintain if not chromium plated. 

A two-stroke engine with the same r.p.m. and cylinder 
volume as a normally aspirated four-stroke engine may 
produce about 60 to 70 per cent, more h.p. Indeed, it 
can be built somewhat smaller, and is simpler in construc- 
tion and easier to maintain. The length of the two-stroke 
is increased if a scavenging pump is used on the free end 
(Alpha) but not if a rotating scavenging pump is placed 
on the side (Wichmann). The scavenging pumps can also 
be placed in front of each cylinder (Sulzcr). 

The lubricating oil consumption of two-stroke engines 
was once considered to be too high, but a modern two- 
stroke compares favourably with that of a four-stroke. 
Improved oil film conditions, etc., for the cylinders have 
overcome many of the problems, especially the coking 
of the exhaust ducts. 

The spacing of the cylinders, i.e. the distance between 
the axes of two adjacent cylinders on the four-stroke is 
from about 1.4 to 1.6 D (D=diam. of the cylinder bore) 
as compared with 1 .7 to 1 .9 D for the two-stroke engine. 
The low values will be attained for the two-stroke engine 
with uniflow scavenging and the high with Curtis scaveng- 
ing, the cooling water space being in the cylinder liner 
itself. 

The four-stroke cylinder liner has no scavenging and 
exhaust ducts and can be of uniform thickness and thus 
evenly cooled, which is important, particularly for un- 
cooled pistons. There will be a better lubricating film and 
the liner wall will be less fouled by exhaust, with longer 
time between overhauls of the piston as the result. 

The four-stroke engine has, therefore, some advantages 
compared with the two-stroke, especially if the two-stroke 
has a symmetrical scavenging and exhaust steering 
diagram. 

SUPERCHARGING OF DIESELS 

It is easier to build a four-stroke diesel with super- 
charging than a two-stroke trunk-piston engine with a 
symmetrical steering diagram. This, and the rapid 
development of supercharging equipment has an effect 
on the competition between the supercharged four-stroke 
and two-stroke full diesel engines. Supercharging will 




Fig. 221. Alpha engine, with hydraulically^perattd clutch and gear 
for controllable-pitch propeller 



[262J 



INSTALLATION OF MACHINERY PROPULSION ENGINES 



increase the output of a normally aspirated four-stroke 
diesel by 60 to 100 per cent. W